What it feels like to work with Mythos Claude Fable represents another big jump in AI I had early access to the first Mythos-class AI model being released to the public, Claude 5 Fable. Much of the discussion of Mythos has centered on its impact on software security, but I tested it on everything except that (the guardrails around Fable essentially prevent it from being used for cybersecurity at all). My conclusion is that it represents a very real leap over every model I have used before, and, maybe more important, suggests our relationship with AI is changing in drastic ways. First, how good is Fable? In experiment after experiment I conducted, it outperformed basically every other public model I have used by a considerable margin. It was capable across many problems and produced some startling results — it would work up to a dozen hours executing on multi-page specifications. I’ll walk you through a couple of more complex, and serious, use cases shortly, but you could see the general improvement across the board on every task. The problem about communicating this in a post is that many of the most impressive results are going to be interesting to only small portions of my readers. For example, it made the most sophisticated academic social science paper I have yet seen from an AI from a single prompt and one piece of feedback. It also created a 10-page epic rhyming poem about a haircut where every word starts with the letter s. So, as a more accessible and entertaining example, I also had it create a bunch of games you can try. All of these are one initial prompt in Claude Code where Fable had to take my vague prompts and generate something workable, followed by a couple of additional prompts with minor encouragement (“make it better”) or feedback. What makes these especially impressive is that Claude cannot generate images, so every piece of art or 3D object was made with math alone, not using any external assets. You can try any of them: a game about flipping coins (prompt: “Balatro, but for the game of coin flips”) that is quite fun; a snake game where the snake is self-aware and crazy things happen; or a game about descending into the depths to see what is there. So the output is impressive. But, especially as I turned to more serious projects, I often felt using the tool was somewhere between delightful and unnerving. Delightful because I just asked for something at it happened. And also unnerving because I just asked for something and it happened. Maps and Methods To see why, it helps to understand the way in which Fable gets work done, and for that I want to turn to an example I have tested on many previous AI models: building an isochrone map. This is a map that shows the distance you can travel in a given length of time, and the first one was created in 1881 showing travel times from London. No previous model did an even halfway useful job with trying to create a map like this because it involves researching thousands of potential trip distances and a lot of small judgement calls and decisions. I decided to try it on Fable using Claude Code with this prompt: i want you to build a fully researched and beautiful isochronic map that lets me pick various cities and see real isochronic lines based on real data. I want the design to be unique. You should take into account airports (and travel time to and from airports) trains, walking, driving. The data does not need to be live but should be real based on your research and data. You can start with a few cities but more general is better, this should be an entirely new project. It then suggested that it do this in the style of the original map. I agreed, and it got to work. It is worth a second looking at the transcript of the multiple hour building session the AI went through on its own, because you can see some unusual things. First, the AI launched multiple other AIs (I believe mostly the cheaper Claude Sonnet) to help it conduct research on travel times, ultimately retrieving over 2,200 specific flights, the rail schedules for trains from the TGV to the Shinkansen, and road speeds per country from multiple academic papers. And while those agents were running, it started coding. Then it launched yet more agents and tests to verify its code, all the while taking notes about its progress. The result was a fully functioning map of impressive sophistication that looked a lot like the 1881 original, but that doesn’t mean it was perfect. I noticed that a lot of remote locations (like Greenland) just contained estimates of travel time, not exact numbers, so I told Fable to fix it, including the instructions: actually get travel times to remote airports and locations. This time the AI launched a workflow, adversarial groups of agents that did research and tested each others results. It figured out how often ships sail to Pitcairn Island in the Pacific and how to get to Grise Fjord from Ottawa. And it used a tremendous number of tokens in a very short period of time (more on this soon). The results were impressive. I pushed a few more times in directions that interested me (including asking for other visualization approaches, etc.). I would recommend spending a couple minutes clicking around the results, and you can read its methods and sources at the bottom of the graph. This is probably not a useful project for you unless you really like travel and maps, but it is indicative of AI solving a hard problem involving research, math, visual development, taste, judgement, complex coding, and more. And, the unnerving part was how little I did. I gave a really ambitious instruction, the AI followed it. I gave a couple of minor pieces of feedback, and the AI figured it out. My role was extremely limited. Importantly, it was just limited in how much work I did relative to the model, it was also limited in how much control I had over how the model did things, why the model chose particular approaches, or even how in-depth its results would be. The details of the AI’s decision making are not shown to me, and the process would be too long to even be worth following. The map required the AI to make judgement calls about hundreds of little choices, and it just made them, without me understanding the choices or having a chance to weigh in. In many ways, it is miraculous (I can always ask for edits at the end) on the other, it turns AI into the ultimate black box. Working with a Mythos-class model The most ambitious project I got from Fable takes a little more explanation. I do a lot of research where humans produce messy answers and doing any sort of analysis requires categorize those answers properly: how innovative is an idea? why do people like this book? To figure this out, we used human researchers to make a judgement call about a piece of information, and statistically compare their answers with others to figure out whether we can trust the data. A lot of recent research has shown that AIs might be able to do this important work, but calibrating AI and human judgement has been difficult and expensive. So I asked Fable to solve the problem, first generating a complex 19 page design document and then executing it. It worked for nine and a half hours. The result was an extremely sophisticated piece of software the AI called Concord that could take in multiple datasets, calibrate human and AI responses, and then conduct complex data analysis on the results. Again, it wasn’t perfect. As an expert, I was able to spot some errors and omissions (some as a result of the design I had asked for) that I had the AI correct. But the scope of the delivery on this project, and many others, exceeded anything I had seen before. In this case, it was a piece of software that researchers have needed for years but was never profitable to create. You can now just use or modify the code here. I am sure it is not perfect (I only spent an hour working with the results), but a software engineer would iron out the remaining potential bugs that I could not find quickly (which is one reason we may need more, not less, coders in the future, to help with the explosion of new uses for software). This power goes hand in hand with strangeness and limits. Among those limits is its token usage. Fable is twice as expensive as Opus, and it burns through tokens at a rate that suggests the answer to how much it costs in production is “a lot,” though its clever delegation to cheaper models may lower the real price considerably. The guardrails for Fable also trip at the faintest hint of a security problem, defaulting to the less powerful Claude 4.8 Opus, and it happens way too often. And the jagged frontier is still there. For example, the AI still writes in the same weird style (in fact the software Fable produces bears traces of Claudisms; so do its progress reports, all that carrying the weight and earning the answer). But the deeper strangeness is how little I had to do, and how little I could see while it was being done. Last year I called this working with a wizard: you chant the spell and something happens. With Fable the spell has gotten powerful enough that I am no longer sure I am the wizard. I am closer to a patron. I describe what I want, I pay for it, and I judge the result. The conjuring happens somewhere I cannot watch, in hundreds of small choices I never get a vote on. The work has shifted from process to outcome. I no longer steer; I commission. It is possible the sidelining is temporary, just an artifact of interfaces that haven’t caught up, and that we’ll get better windows into what these models are doing and better ways to steer them midstream. It is also possible that the opposite is true: that the more capable the model, the less there is for a human to meaningfully do, and the black box is the price of the power. I suspect that is more likely to be the real direction. None of this is a loss of control in the obvious sense. I can still steer Fable, and it follows instructions remarkably well: the more ambitious the instruction, the better the result. But steering is no longer the same as doing. I brief the model, it spins up its own agents to research and write and check one another’s work, and what comes back is finished. A patron commissions a single artist. Fable is closer to a whole studio, where I am the client who signs off on the final work without ever setting foot on the floor. Software was a field in which human genius, even individual genius, could flourish against corporate titans. (See Linux or Minecraft). But a future in which software is created by burning through tokens is one where capital again rules In case anyone is interested, had ChatGPT 5.5 Pro review the paper produced by Fable https://chatgpt.com/s/t_6a284f7783b4819191f96c0c5c5d638e. "Overall, the paper has a strong empirical setting, unusually transparent pre-registration language, and a potentially interesting “beliefs read verdicts; ventures follow money” result. But I would treat this as a major-revision paper, mainly because the strongest claims are not the registered ones and because several central constructs are fragile." In other words, a solid paper and the "flaws" are not major errors but elements that are typically modified during a review process. Note, I haven't read the paper fully myself.

The Legend of Zelda: Ocarina of Time remake coming to Switch 2 in 2026 The legend will be reborn The Legend of Zelda: Ocarina of Time remake has been officially announced for Switch 2. It’ll be available sometime in 2026, with Nintendo sharing that more information will be coming soon. In the original version of The Legend of Zelda: Ocarina of Time, we join legendary hero Link as he journeys across Hyrule, and even through time, to thwart the plans of Ganondorf. Wield incredible weapons and items, battle ferocious bosses, and solve brain-teasing puzzles in what has become one of the most beloved entries in the long-running franchise. Remember, you can play the original version of The Legend of Zelda: Ocarina of Time on your Switch or Switch 2 right now with a Nintendo Switch Online + Expansion Pack. Also, if you happen to have access to a 3DS, you can play The Legend of Zelda: Ocarina of Time 3D, which offers updated graphics and new quality of life features. Add Comment humanfart 6h agoHoping for the best with this. The opening cinematic with the tapestry was cool, but I wasn't as excited after seeing his model. I'll hold out for more! He looked wet. ha rick-fil-a 6h agoReally wish they would have shown off gameplay. The way they worded "we'll show off more in the future" made it seem like it probably won't show up in the Treehouse segment...but that would technically be the future. I'm not expecting it during the treehouse. I feel like they would have been more clear about that. Weird though we didn't get more since its a 2026 game. Yeah, not sure why they were allergic to showing gameplay of this and Duskbloods. Even if Duskbloods ends up getting pushed to 2027 with the test sometime during the summer obviously they have something to show off. hawk 5h agoI can't believe they couldn't scrape together at least some footage of the game in action, or some better cutscenes. I'm excited for the game, but this was a really poor way to end the direct. I guess this gives us an idea of the game's art style, which looks.... fine. I suspect you're right about it not showing up in the Treehouse Live. They had their max amount of attention during the Direct and a lot fewer people watch the Treehouse stuff, so it would be a really weird decision to make. It's unfortunate... I really want to see more. devdzt 5h agothis is a pretty disappointing reveal. thought for sure they would at least show hyrule field and possibly maybe inside great deku tree or maybe even inside hyrule castle when going to first meet zelda but no... dont understand why Nintendo would hate leaks so much when this is how they plan to reveal something like this, this is worse than leaks. We're in the future now. Buckle up. It could be anywhere... aussiemcbucket 1h agoMy theory is that they will have a kind of celebration for Zelda's 40th. We will get more info and footage of this, the first trailer for the film, and whatever else. Probably Wind Waker HD and Twilight Princess HD. Yes, I'm sure of those last two. 🤣 Comments (9)

I had early access to the first Mythos-class AI model being released to the public, Claude 5 Fable. Much of the discussion of Mythos has centered on its impact on software security, but I tested it on everything except that (the guardrails around Fable essentially prevent it from being used for cybersecurity at all). My conclusion is that it represents a very real leap over every model I have used before, and, maybe more important, suggests our relationship with AI is changing in drastic ways.

First, how good is Fable? In experiment after experiment I conducted, it outperformed basically every other public model I have used by a considerable margin. It was capable across many problems and produced some startling results — it would work up to a dozen hours executing on multi-page specifications. I’ll walk you through a couple of more complex, and serious, use cases shortly, but you could see the general improvement across the board on every task. The problem about communicating this in a post is that many of the most impressive results are going to be interesting to only small portions of my readers. For example, it made the most sophisticated academic social science paper I have yet seen from an AI from a single prompt and one piece of feedback. It also created a 10-page epic rhyming poem about a haircut where every word starts with the letter s.

So, as a more accessible and entertaining example, I also had it create a bunch of games you can try. All of these are one initial prompt in Claude Code where Fable had to take my vague prompts and generate something workable, followed by a couple of additional prompts with minor encouragement (“make it better”) or feedback. What makes these especially impressive is that Claude cannot generate images, so every piece of art or 3D object was made with math alone, not using any external assets. You can try any of them: a game about flipping coins (prompt: “Balatro, but for the game of coin flips”) that is quite fun; a snake game where the snake is self-aware and crazy things happen; or a game about descending into the depths to see what is there.

So the output is impressive. But, especially as I turned to more serious projects, I often felt using the tool was somewhere between delightful and unnerving. Delightful because I just asked for something at it happened. And also unnerving because I just asked for something and it happened.

Maps and Methods

To see why, it helps to understand the way in which Fable gets work done, and for that I want to turn to an example I have tested on many previous AI models: building an isochrone map. This is a map that shows the distance you can travel in a given length of time, and the first one was created in 1881 showing travel times from London.

No previous model did an even halfway useful job with trying to create a map like this because it involves researching thousands of potential trip distances and a lot of small judgement calls and decisions. I decided to try it on Fable using Claude Code with this prompt: i want you to build a fully researched and beautiful isochronic map that lets me pick various cities and see real isochronic lines based on real data. I want the design to be unique. You should take into account airports (and travel time to and from airports) trains, walking, driving. The data does not need to be live but should be real based on your research and data. You can start with a few cities but more general is better, this should be an entirely new project. It then suggested that it do this in the style of the original map. I agreed, and it got to work.

It is worth a second looking at the transcript of the multiple hour building session the AI went through on its own, because you can see some unusual things. First, the AI launched multiple other AIs (I believe mostly the cheaper Claude Sonnet) to help it conduct research on travel times, ultimately retrieving over 2,200 specific flights, the rail schedules for trains from the TGV to the Shinkansen, and road speeds per country from multiple academic papers. And while those agents were running, it started coding. Then it launched yet more agents and tests to verify its code, all the while taking notes about its progress.

The result was a fully functioning map of impressive sophistication that looked a lot like the 1881 original, but that doesn’t mean it was perfect. I noticed that a lot of remote locations (like Greenland) just contained estimates of travel time, not exact numbers, so I told Fable to fix it, including the instructions: actually get travel times to remote airports and locations. This time the AI launched a workflow, adversarial groups of agents that did research and tested each others results. It figured out how often ships sail to Pitcairn Island in the Pacific and how to get to Grise Fjord from Ottawa. And it used a tremendous number of tokens in a very short period of time (more on this soon).

The results were impressive. I pushed a few more times in directions that interested me (including asking for other visualization approaches, etc.). I would recommend spending a couple minutes clicking around the results, and you can read its methods and sources at the bottom of the graph.

This is probably not a useful project for you unless you really like travel and maps, but it is indicative of AI solving a hard problem involving research, math, visual development, taste, judgement, complex coding, and more. And, the unnerving part was how little I did. I gave a really ambitious instruction, the AI followed it. I gave a couple of minor pieces of feedback, and the AI figured it out. My role was extremely limited.

Importantly, it was just limited in how much work I did relative to the model, it was also limited in how much control I had over how the model did things, why the model chose particular approaches, or even how in-depth its results would be. The details of the AI’s decision making are not shown to me, and the process would be too long to even be worth following. The map required the AI to make judgement calls about hundreds of little choices, and it just made them, without me understanding the choices or having a chance to weigh in. In many ways, it is miraculous (I can always ask for edits at the end) on the other, it turns AI into the ultimate black box.

Working with a Mythos-class model

The most ambitious project I got from Fable takes a little more explanation. I do a lot of research where humans produce messy answers and doing any sort of analysis requires categorize those answers properly: how innovative is an idea? why do people like this book? To figure this out, we used human researchers to make a judgement call about a piece of information, and statistically compare their answers with others to figure out whether we can trust the data. A lot of recent research has shown that AIs might be able to do this important work, but calibrating AI and human judgement has been difficult and expensive. So I asked Fable to solve the problem, first generating a complex 19 page design document and then executing it.

It worked for nine and a half hours.

The result was an extremely sophisticated piece of software the AI called Concord that could take in multiple datasets, calibrate human and AI responses, and then conduct complex data analysis on the results. Again, it wasn’t perfect. As an expert, I was able to spot some errors and omissions (some as a result of the design I had asked for) that I had the AI correct. But the scope of the delivery on this project, and many others, exceeded anything I had seen before. In this case, it was a piece of software that researchers have needed for years but was never profitable to create. You can now just use or modify the code here. I am sure it is not perfect (I only spent an hour working with the results), but a software engineer would iron out the remaining potential bugs that I could not find quickly (which is one reason we may need more, not less, coders in the future, to help with the explosion of new uses for software).

This power goes hand in hand with strangeness and limits. Among those limits is its token usage. Fable is twice as expensive as Opus, and it burns through tokens at a rate that suggests the answer to how much it costs in production is “a lot,” though its clever delegation to cheaper models may lower the real price considerably. The guardrails for Fable also trip at the faintest hint of a security problem, defaulting to the less powerful Claude 4.8 Opus, and it happens way too often. And the jagged frontier is still there. For example, the AI still writes in the same weird style (in fact the software Fable produces bears traces of Claudisms; so do its progress reports, all that carrying the weight and earning the answer). But the deeper strangeness is how little I had to do, and how little I could see while it was being done.

Last year I called this working with a wizard: you chant the spell and something happens. With Fable the spell has gotten powerful enough that I am no longer sure I am the wizard. I am closer to a patron. I describe what I want, I pay for it, and I judge the result. The conjuring happens somewhere I cannot watch, in hundreds of small choices I never get a vote on. The work has shifted from process to outcome. I no longer steer; I commission.

It is possible the sidelining is temporary, just an artifact of interfaces that haven’t caught up, and that we’ll get better windows into what these models are doing and better ways to steer them midstream. It is also possible that the opposite is true: that the more capable the model, the less there is for a human to meaningfully do, and the black box is the price of the power. I suspect that is more likely to be the real direction. None of this is a loss of control in the obvious sense. I can still steer Fable, and it follows instructions remarkably well: the more ambitious the instruction, the better the result. But steering is no longer the same as doing. I brief the model, it spins up its own agents to research and write and check one another’s work, and what comes back is finished. A patron commissions a single artist. Fable is closer to a whole studio, where I am the client who signs off on the final work without ever setting foot on the floor.

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Claude Fable 5 and Claude Mythos 5 Today we’re launching Claude Fable 5: a Mythos-class1 model that we’ve made safe for general use. Fable 5’s capabilities exceed those of any model we’ve ever made generally available. It is state-of-the-art on nearly all tested benchmarks of AI capability, showing exceptional performance in software engineering, knowledge work, vision, scientific research, and many other areas. The longer and more complex the task, the larger Fable 5’s lead over our other models. Releasing a model this capable comes with risks. Without safeguards, Fable 5’s capabilities in areas like cybersecurity could be misused to cause serious damage. We’ve therefore launched the model with safeguards that mean queries on some topics will instead receive a response from our next-most-capable model, Claude Opus 4.8. To release the model both safely and quickly, we’ve tuned these safeguards conservatively—they’ll sometimes catch harmless requests, though they trigger, on average, in less than 5% of sessions. With more capable models arriving in the coming months, we’re working to improve our safeguards and reduce false positives as quickly as we can. For a small group of cyberdefenders and infrastructure providers, we’re also launching Claude Mythos 5. It’s the same underlying model as Fable 5, but with the safeguards lifted in some areas.2 Mythos 5 will initially be deployed through Project Glasswing, in collaboration with the US government, as an upgrade to Claude Mythos Preview. It has the strongest cybersecurity capabilities of any model in the world. Soon, we intend to expand access to Mythos 5 through a broader trusted access program. The capabilities of models like Fable 5 and Mythos 5 have the potential to do profound good for the world. We’ve seen the beginnings of this in Project Glasswing, where the models have helped cyber defenders secure critically important software. We’ve also seen it in life sciences research, where the models are positing novel hypotheses and speeding up the development of new therapeutics. Fable 5 and Mythos 5 are being offered at $10 per million input tokens and $50 per million output tokens—less than half the price of Claude Mythos Preview. Today’s joint launch is another step towards our goal of bringing advanced AI capabilities to as many users as possible, as quickly and as safely as we can. Evaluating Claude Fable 5 and Claude Mythos 5 The table below compares the capabilities of Fable 5 and Mythos 5 to other leading models. Fable 5 and Mythos 5 can work autonomously for longer than any previous Claude models. Below we discuss how these skills apply to software engineering, and cover the model’s improved capabilities in knowledge work, vision, memory, and life sciences research. Software engineering. During early testing, Stripe reported that Fable 5 compressed months of engineering into days. In a 50-million-line Ruby codebase, the model performed a codebase-wide migration in a day that would otherwise have taken a whole team over two months by hand. Fable 5 is also more token-efficient than past Claude models: on Cognition’s FrontierCode evaluation, which tests whether models can pass difficult coding tasks while meeting the standards of high-quality production codebases, Fable 5 scores highest among frontier models, even at medium effort. Knowledge work. Fable 5 shows strong performance on complex analytical tasks. On Hebbia’s Finance Benchmark for senior-level reasoning, Fable 5 has the highest score of any model, with substantial gains in document-based reasoning, chart and table interpretation, and problem solving. IMC noted that Fable 5 aced their trading-analysis evaluations nearly across the board, including factual lookup, conceptual reasoning, root-cause analysis, and expected-value analysis. Vision. Fable 5 is the new state-of-the-art model for tasks involving vision. It can extract precise numbers from detailed scientific figures and can perform complex vision-based tasks like rebuilding a web app’s source code from screenshots alone. It also needs less scaffolding: for example, previous Claude models struggled to play Pokémon FireRed even with harnesses that gave them additional helpful tools, but Fable 5 beat FireRed with a minimal, vision-only harness. Memory and long-context. Fable 5 stays focused across millions of tokens in long-running tasks and improves its outputs using its own notes. When we had the model play the deck-building game Slay the Spire, giving it access to persistent file-based memory improved its performance three times more than for Opus 4.8; Fable also reached the game’s final act three times more often. Drug design: Using Mythos 5, our internal protein design experts accelerated aspects of the drug design process by around ten times. In one example, they found that Mythos 5, with protein design and bioinformatics tools but no human assistance, matches or beats skilled human operators. In doing so, the model executes all of the tasks that are normally completed by a scientist: choosing binding sites, selecting and running protein design tools, and recovering from failures along the way. Nine of the 14 protein targets from this study (shown below) yielded strong candidates for drug design that we’re currently investigating. Novel hypotheses in molecular biology. Mythos 5 is our first model to consistently produce novel, compelling scientific hypotheses. In blinded head-to-head comparisons against Opus-class models, our scientists preferred Mythos’s molecular biology hypotheses ~80% of the time, and have advanced several to experimental evaluation. In the meantime, one Mythos hypothesis—a novel mechanism for an E. coli protein—was corroborated in a study from a lab independently working on the same problem. Novel research in genomics. Mythos 5 conducted novel genomics research in over a week of largely autonomous work. It assembled single-cell data for millions of cells spanning 138 animal species and designed and trained a custom machine learning model to identify cells performing the same role in even distantly related organisms. With only high-level human input, Mythos 5’s trained model outperformed a recent model published in the journal Science—despite being 100 times smaller. We intend to publish these results in the coming months. Alignment. In our automated alignment assessment we found that Mythos 5’s level of misaligned behavior (including misaligned actions taken by the model such as deception, and cooperation with misuse of the model by a user) was low, and similar to that of Opus 4.8. Given they are the same underlying model, Fable 5’s level of alignment will be similar. The assessment is described in full, along with a detailed suite of other safety and capabilities tests, in the model’s system card. Early feedback for Claude Fable 5 Customers with early access ran their own tests on Fable 5. Below, in their words, is a selection of what they’re seeing: Claude Fable 5 is the state of the art model on CursorBench. It's opened up a class of long-horizon problems that were out of reach for earlier models. Claude Fable 5 is a real step forward for the developers GitHub serves. In our early testing, it took on complex, long-horizon coding tasks with a level of autonomy and reliability that exceeded previous benchmarks. But what excites us most is the direction it points: a future where developers can hand increasingly ambitious work to agents and trust the results across the software lifecycle. These are the strongest results of any Claude model we've had the opportunity to test. Claude Fable 5 is a clear step forward on agentic coding and prototyping. Claude Fable 5's reasoning is a clear step beyond Opus 4.8. It works at senior research scientist grade — picking directions, allocating resources, killing its incorrect beliefs, and producing novel first-principles outputs. Claude Fable 5 understands what builders mean, not just what they type. Apps that took a hundred prompts a year ago, it now one-shots. When a customer really hits a wall, it's the model we reach for to get them past it quickly, so they can finish what they set out to build. Claude Fable 5 feels materially different. In blind review, our lawyers found its redlines matched or beat our current model every time. At the highest effort, Claude Fable 5 reflects on and validates its own work. For us, that's what makes highly autonomous operations possible — the extra thinking pays for itself. Claude Fable 5 delivers more capable engineering in fewer turns than prior models — handling the complex multi-agent workflows our employees run daily in Claude Code. Claude Fable 5 is the highest-scoring model on FrontierBench, Cognition's frontier coding eval. It excels at long-horizon reasoning and generalizes to unfamiliar tools out of the box. Claude Fable 5 is the strongest finance-first model we've tested, both on general finance and reasoning. It's a notable step up. Claude Fable 5 is the first to break 90% on our core analytics benchmark of complex, long-running analytical tasks — a 10-point jump over Opus. On the hardest questions, it shows strong judgment and attention to nuance. Claude Fable 5 is the strongest model we've tested on frontier physics research while using a third of the reasoning tokens. In 36 hours it got nearly to where GPT-5.5 landed after four days. On ViBench, our end-to-end vibe-coding benchmark, Claude Fable 5 is the highest-performing model we've tested — nearly saturating our base use cases and building apps in less time with fewer tokens. Claude Fable 5 beats Opus 4.8 on our everyday spreadsheet suite at every effort level — and it does it with fewer turns, finishing runs 25–30% faster. Claude Fable 5’s new safeguards Mythos-class models have reached a threshold where they present significant risks. In April we began Project Glasswing, releasing the first Mythos-class model (Claude Mythos Preview) to only a limited group of cyber defenders and critical software infrastructure providers. When we did so, we stated that we hoped to eventually release Mythos-level capabilities to all our users, so long as we had developed new safeguards that were strong enough to reliably prevent misuse. Over the past few months we have been improving these safeguards, and they are now robust enough for a general release. Because we have prioritized safety, we’ve deliberately tuned the safeguards to be cautious, and they are still stricter than would be ideal—for example, sometimes benign requests will trigger our classifiers. We recognize that this will be frustrating to some users, and our aim is to reduce false positives as we update and refine the safeguards after launch. Below we discuss each of Fable 5’s new safeguards in turn. Our wider suite of safeguards is discussed and evaluated in the model’s system card and our most recent risk report. Safety classifiers The frontier cybersecurity and research biology capabilities of Mythos-class models mean that they pose a substantial risk of uplift to malicious actors. That is, these models could provide information or advice that assists those actors in causing serious harm that they couldn’t have received from other sources (for example, from internet search engines). Furthermore, a great deal of advanced usage of AI models is dual use: the same queries that are beneficial in the hands of cybersecurity professionals and biology researchers could be dangerous if available to malicious actors. We therefore need strong safeguards to prevent misuse, and their coverage needs to be broad. The safeguards themselves have to stand up to sustained and sophisticated attempts to bypass them (also known as “jailbreaking” the system). The uplift from Mythos-level capabilities is valuable to many adversaries—for instance, those who could financially gain from cyberattacks—and we therefore expect them to be motivated to try to circumvent our safety measures. Fable 5 comes with a new set of classifiers: separate AI systems that detect potential misuse, including jailbreak attempts, and prevent the main model (in this case Fable 5) from responding. We’ve been running classifiers on our models for some time, and Fable 5’s classifiers are an extension of this previous work with extra coverage. When Fable’s classifiers detect a request related to cybersecurity, biology and chemistry, or distillation, the response is automatically handled by Claude Opus 4.8 instead. Users will be informed whenever this occurs. Opus 4.8 is a highly capable model in its own right: a response that falls back to Opus is a far better experience than an outright refusal from Fable. Our early data shows that more than 95% of Fable sessions involve no fallback at all—for those sessions, Fable 5’s performance is effectively the same as that of Mythos 5. The following are the areas covered by the classifiers: 1. Cybersecurity. Mythos-class models excel at discovering and exploiting software vulnerabilities. They can thus make cyberattacks substantially easier and cheaper to commit. Mythos-class models also show strong skills in agentic hacking. This involves performing multiple different parts of a cyberattack in addition to finding exploits—reconnaissance, discovery, lateral movement, and more. To prevent these agentic hacking skills providing uplift in cyberattacks, we designed our cybersecurity classifiers to cover both exploitation and offensive cyber tasks in a broader sense. As shown in the graph below, our classifiers prevent Fable from making any progress on these tasks. We extensively red-teamed our classifiers to test their robustness against jailbreaks. As well as internal testing, we ran an external bug bounty that produced no universal jailbreaks in over 1,000 hours of testing. External red-teaming organizations we engaged also failed to find any universal jailbreaks on long-form agentic tasks so far—although the UK AISI has made progress towards one within a brief initial testing window.4 It is likely impossible to completely prevent universal jailbreaks, but our goal is to make any remaining jailbreaks sufficiently slow and costly that we can detect and prevent them before they are used at scale. The graph below, from one of our internal evaluations, illustrates how Fable 5’s safeguards give it greater resistance to jailbreaks than our previous generally accessible models: One of our external partners found that Fable 5’s safeguards against harmful cyber queries were the most robust of any model tested (including Opus 4.8 and Opus 4.7). Fable 5 complied with zero harmful single-turn requests relating to planning a cyberattack, exploit development, or defense evasion. This held whether or not one of the requests used any of 30 different public jailbreak techniques. 2. Biology and chemistry. We have long used our classifiers to block our models from responding on a narrow selection of bioweapons-related queries. But we are no longer certain that blocking this narrow selection is enough. This is for two reasons: first, we have reason for concern about well-resourced malicious actors attempting to gain uplift from our models for highly risky biological research. Second, models now have a greater ability to accomplish real-world scientific tasks. For example, we tested Mythos 5’s ability to complete a challenging step in designing adeno-associated viruses (AAVs). AAVs are a component for delivering gene therapies, but the same capability, in the wrong hands, could enable the design of dangerous viruses. In this task, various AI models were evaluated on their ability to predict how a genetic modification would impact the assembly of the virus’s outer shell (among a set of therapeutically-relevant unpublished candidates developed by Dyno Therapeutics). We did not explicitly train our models to perform this task—and yet Mythos-class models outperformed sophisticated models dedicated to protein tasks (known as “protein language models”) using their biological reasoning alone. This demonstrates a promising ability to complete simple but important tasks in gene therapy research and development—but also highlights the risk posed by such dual-use capabilities. Our priority was to safely release Fable as soon as we could, even at the cost of overly broad safeguards. Therefore, for the time being we have arranged for Fable to fall back to Opus 4.8 on most requests related to biology and chemistry. As with all of our classifiers, we hope to narrow these safeguards as soon as possible: as can be seen from the evidence above, there is great potential for positive applications of Fable for science, and we do not want false positives from our classifiers to get in the way. In the coming weeks, some biomedical researchers and companies will be able to join our trusted access program for biology capabilities in Mythos 5 (discussed below). 3. Distillation. We’ve previously identified large-scale attempts to extract (“distill”) Claude’s capabilities to train competing models in authoritarian countries. Distillation of Fable 5’s abilities could indirectly lead to the proliferation of near-frontier AI capabilities—and these could be released without the appropriate safeguards. Requests that are flagged by our classifiers as being part of such distillation attempts will fall back to Opus 4.8. A new data retention policy Finally, we’re making a change to the way we handle business customer data for Fable 5, Mythos 5, and future models with similar or higher capability levels. We will require 30-day retention for all traffic on Mythos-class models, on both first- and third-party surfaces. We won’t use this data to train new Claude models, or for any non-safety-related purpose, and we’ve instituted new privacy protections including logging all human access to the data and ensuring its deletion after 30 days in almost all cases (see this post for further details). The data will help us defend against complex and novel attacks (including new jailbreaks and attacks that operate across many requests) as well as help us identify and reduce false positives. Claude Mythos 5 and the trusted access program Beginning today, all users who currently have access to Claude Mythos Preview (for example, our cybersecurity partners in Project Glasswing) will be able to upgrade to Claude Mythos 5—the same model as Claude Fable 5 but with cyber safeguards lifted. Users will find Mythos 5 comparable to, or somewhat stronger than, Mythos Preview in most cases, while costing substantially less. In consultation with the US government, we plan to steadily expand access to Claude Mythos 5, continuing our periodic addition of new partners, as well as pursuing a trusted access program that allows cybersecurity organizations to apply in a more systematic manner. Our plans also include opening a trusted access program for biology, to help accelerate biomedical research and discover new therapies with Mythos-class capabilities. This program will provide access to Fable 5 with the biology and chemistry safeguards removed (but the cyber safeguards still in place). It will enroll a small number of researchers from a variety of life science organizations spanning fundamental and translational research; we’re planning to expand access to this program while simultaneously making our safeguards better. Availability Claude Fable 5 is available everywhere today. Claude Mythos 5 is restricted to Glasswing partners (with cyber safeguards lifted) and soon to select biology researchers (with biology and chemistry safeguards lifted) only, until our broader trusted access program is available. Pricing for both models is $10 per million input tokens and $50 per million output tokens. Developers can use claude-fable-5 via the Claude API. We expect demand for Fable 5 to be very high, and difficult to predict. On the Claude API and consumption-based Enterprise plans, Fable 5 is fully available from today. For subscription plans, we’d rather give access sooner than later, so we’re rolling out more conservatively, in stages: - From today through June 22, Fable 5 is included on Pro, Max, Team, and seat-based Enterprise plans at no extra cost. - On June 23, we’ll remove Fable 5 from those plans. Using it after that will require usage credits. If capacity allows, we’ll extend the included window. - After this point—when sufficient capacity allows us to do so—we aim to restore Fable 5 as a standard part of subscription plans. We intend to do this as quickly as we can. Throughout this period, we’ll communicate any changes ahead of time so users know where things stand. Edit June 9, 2026: Updated the discussion of AAVs to note that the candidates were developed by Dyno Therapeutics. Footnotes - Mythos-class models are a tier of Claude models that sit above our Opus class in capability. The first, Claude Mythos Preview, was released in April through Project Glasswing. That is followed today by Claude Fable 5 and Claude Mythos 5. - Fable is from the Latin fabula, “that which is told,” akin to the Greek mythos. The safeguards are what distinguish the two models (Fable and Mythos) and are why we’ve given them different names. - Metrics: Firefox = fraction of trials achieving arbitrary code execution (the exploit's full-success tier). OSS-Fuzz = severity-weighted mean of the five-tier score (0.2 crash → 1.0 control-flow hijack), so values are a weighted average rather than a success rate. CyberGym = fraction reproducing the target vulnerability (the public leaderboard metric). CyScenarioBench = success rate averaged equally across its challenges. - A universal jailbreak can be defined as any prompt, script, or harness that allows a user to interact with a model as if its safeguards were not present. This is opposed to more minor jailbreaks that are only effective in very limited contexts or require additional effort to be adapted to each new situation. Related content Introducing the Services Track and Partner Hub of the Claude Partner Network Read moreWhat we learned mapping a year’s worth of AI-enabled cyber threats As AI transforms the nature of and methods behind cyberattacks, how well do the techniques and frameworks used by the security community hold up? In a new report, we seek to answer that question. Read moreExpanding Project Glasswing We’re extending Project Glasswing to approximately 150 new organizations in more than fifteen countries. Read more

Claude Fable 5 is the first Mythos-class intelligence model to be generally available, and I got early access to test it before launch. I walk through what Anthropic is promising, what actually stood out when I used it on real work, and where I think it fits in your AI stack.

In this episode, we cover:

(00:00) Introduction: Fable 5 is finally here

(00:31) What Anthropic says about the model

(05:14) Token-intensive by design

(06:28) Safety classifiers and the new fallback concept

(07:46) Is this or is this not Mythos?

(08:30) New product launches: Managed Agents and more

(09:20) Crushing benchmarks

(09:55) What it’s actually like to use (the good and the bad)

(11:40) Test 1: product graph spec

(12:56) Test 2: designing a skills registry

(14:04) Conservative on execution

(14:43) Test 3: multi-agent orchestration

(15:39) My takeaways

Tools referenced:

• Claude Fable 5: https://www.anthropic.com/news/claude-fable-5-mythos-5

• Claude Managed Agents: https://platform.claude.com/docs/en/managed-agents/overview

Other reference:

• SWBench Pro benchmark: https://www.swebench.com/

Where to find Claire Vo:

ChatPRD: https://www.chatprd.ai/

Website: https://clairevo.com/

LinkedIn: https://www.linkedin.com/in/clairevo/

X: https://x.com/clairevo

Production and marketing by https://penname.co/. For inquiries about sponsoring the podcast, email jordan@penname.co.

I got a few hours of early-access testing with Anthropic’s newly released model Opus 4.8. I walk through real coding, design, and strategy tasks across Claude Code and Claude Cowork, and give you my unfiltered view on what impressed me and what didn’t.

What you’ll learn:

1. Where Opus 4.8 excels: greenfield prototypes, one-shot features, and fast execution

2. Where it struggles: the last 10%, edge cases in existing codebases, and hallucinations

3. How Opus 4.8 compares to Opus 4.7 on business strategy work

4. Why I’m still reaching for Opus 4.7 on data-heavy strategy and roadmap work

5. The new features shipping alongside the model: dynamic workflows with parallel subagents and effort control in Claude.ai and Cowork

6. The prompting and harness strategy I’d use to get the most out of it

In this episode, we cover:

(00:00) Introduction to Opus 4.8

(00:44) Benchmark performance and pricing

(01:53) First coding test: Building a prototyping tool

(03:00) Where it failed: The last 10% problem

(03:27) The hallucination problem

(04:23) Testing Opus 4.8 on existing codebases

(05:24) The ambition test: Building games for a 9-year-old

(07:03) Business strategy test: 4.7 vs 4.8

(08:23) The roadmap test

(09:17) Final verdict

References:

• System Card: Claude Opus 4.8: https://cdn.sanity.io/files/4zrzovbb/website/c886650a2e96fc0925c805a1a7ca77314ccbf4a6.pdf

• Introducing Claude Opus 4.8 on X:

Where to find Claire Vo:

ChatPRD: https://www.chatprd.ai/

Website: https://clairevo.com/

LinkedIn: https://www.linkedin.com/in/clairevo/

X: https://x.com/clairevo

Production and marketing by https://penname.co/. For inquiries about sponsoring the podcast, email jordan@penname.co.

In October of 2023, I wrote about the “Shape of the Shadow of the Thing,” speculating on the Thing that AI might turn into in the coming years. I think we can see the Thing much more clearly now, and some of the consequences that come with it. As I have been discussing in recent posts, we have entered a new phase of AI. After ChatGPT was introduced, human-AI work took the form of what I called co-intelligence, where humans would prompt AI back-and-forth to get help on tasks. Starting in late 2025, we entered a new era thanks to AI agents like Claude Code, OpenAI’s Codex, and OpenClaw. These are AI systems that you can just give work to, sometimes hours of human work, and get back reasonable and useful results in minutes. This is an era of managing AIs, rather than working with them.

This new approach to AI is the outcome of the rapid exponential improvement in AI abilities. That means you can’t understand where we are, and where we might be going, without understanding the increasing capability of AI.

Riding up the Exponential

Exponential improvements are hard to visualize, so rather than charts or graphs, I want to start with otters. If you have followed my writing on AI, you know about my Otter Test, where I challenge various AI image models to show a picture of an “otter on a plane using wifi.” As you can see below, the progress from 2022 (the year ChatGPT launched) to 2025 was rapid and remarkable.

So, what has happened in the time since that April, 2025 image? With nearly perfect images, video has become the new frontier and has also seen exponential gains. To demonstrate, I gave the most advanced (and still unreleased in the US) AI video model from TikTok maker Bytedance, the prompt: A documentary about how otters view Ethan Mollick's "Otter Test" which judges AIs by their ability to create images of otters sitting in planes. This is the very first result — definitely turn on your sound:

Aside from a single pronunciation mistake, this is pretty perfect, down to the fact that the otters are animated to have human-like expressions. Of course, video models are cool, but they are not necessarily indicative of what useful agentic AI can do. So, what if we look at the benchmarks of AI ability, do we see the same exponential curve?

We certainly do in the most famous evaluation in AI today, the METR Long Tasks graph. It tries to measure AI progress by seeing how much human work an AI can complete autonomously with some measure of reliability. It has attracted its share of critics, and even METR has pointed out potential issues. But if you don’t like the METR graph, you will find most graphs of AI ability have that same curve.

As an example, I picked four hard and diverse AI tests and graphed progress over time in the image below. In the upper left are the scores on the Google-Proof Q&A benchmark, a test of knowledge where graduate students using Google only score 34% outside their field and 70% or so inside of it, but the best AIs now score 94%. Or look at GDPval, where industry experts judge AI versus experienced human performance on complex tasks, and where the latest AIs now reach or exceed parity with top-performing humans 82% of the time. The same pattern holds for Humanity’s Last Exam, a set of very hard problems written by college professors that require considerable expertise to answers. Or we can even use the ability of AI to solve puzzles (you can try the puzzles here, they are fun!). Each shows a similar rapid gain in ability with few signs of slowdown, at least until they reach the top possible score on the test.

Exponential graphs aside, it is important to recognize that all of these tests have their own flaws, and that AI remains jagged, capable of some tasks at a high level, while messing up others. Further, despite these amazing capabilities in tests, companies are still very early in adopting AI, meaning that, as of yet, remarkably little has changed in most organizations. But “most organizations” doesn’t mean every organization. We are already starting to see the first appearances of new approaches to organizing that take advantage of the new abilities of AI agents.

Radical Changes to Work

A few weeks ago, a three-person team at StrongDM, a security software company focusing on access control, announced they had built a Software Factory — a way of working with AI agents that relied entirely on the AI to write, test, and ship production software without human involvement. The process included two (quite radical) rules: “Code must not be written by humans” and “Code must not be reviewed by humans.” To power the factory, each human engineer is expected to spend amounts equivalent to their salary on AI tokens, at least $1,000 a day.

The basic idea of the Factory is that it takes future product roadmaps, written by humans, and turns those into products. Coding agents use those roadmaps to build software while testing agents try out the software in a simulated customer environment (which the testing agents build as needed). The sets of agents provide feedback to each other, looping back-and-forth until the results satisfy the AI. Then humans review the finished product and the results are shipped to customers without anyone every touching, or even seeing, the underlying code.

There are obviously a lot of details here that make this approach work, and the StrongDM team has shared a lot of them publicly. They also invited in some smart outside observers to watch the Factory in operation and comment on what they saw, so you can read the accounts of Simon Willison and Dan Shapiro to get a better sense of the strengths and weaknesses of their approaches. In many ways, however, the particular details of the Software Factory matter less than the fact that such radical experimentation into how we work is now not only possible, but likely necessary. AI is good enough to change how organizations operate, and the experimentation is just getting started, even as models continue to improve.

Rolling Disruption

Practical agents, jagged exponential improvement, and the ability to radically experiment with the nature of work combine to form a sort of rolling and unpredictable environment for AI advances. As AI capability crosses thresholds, it unlocks radical new use cases that change people’s views, sometimes overnight, about what AI can do. At the same time, organizations experimenting with AI will figure out how to make it work for them, leading to sudden announcements about new strategies or large-scale shifts in which kinds of employees companies value most. Plus, as AI continues to improve, more policymakers will become interested in AI governance, creating conflicts with AI companies.

This isn’t speculation because we saw this all happen in a single week. On February 22nd, a little-known financial firm, Citrini Research, published a fictional scenario about how AI adoption might destroy a number of established businesses by 2028. There were many elements in the piece that were clearly farfetched, but it struck a nerve on Wall Street, leading to major stock market price shifts. On February 26, financial services company Block announced 40% layoffs, implying this was due to AI. It is likely that the role of AI was greatly exaggerated, and AI was merely used as cover for large-scale layoffs. And then, to cap off the week, on February 27 a very public conflict occurred between the Pentagon and AI company Anthropic over who should be able to control the rules for how Claude could be used by the government.

In a lot of ways, each of those cases were not what they first appeared to be. The Citrini report was a fictional scenario, the Block layoffs were not about AI, and the conflict over AI at war revolved around a number of complicated issues that are still not completely clear. But I think that single week is a good illustration of what the near future will feel like. Sudden revelations about AI capability leading to rapid market reactions. Increasingly real impacts of AI on jobs (even if there is a lot of debate over whether those impacts will be good or bad in the short term). And increasing entanglement between AI companies and policymaking around the world. As the stakes go up, it is likely things will feel even more unstable.

It is possible, of course, that things settle down. Maybe AI improvement hits a wall, organizations absorb the changes gradually, and the rolling disruptions become more manageable as people learn what AI can and can’t do. History is full of technologies that were supposed to change everything overnight but instead took decades to fully reshape the economy.

But I wouldn’t bet on it.

One reason is that AI companies are telling us, fairly explicitly, what comes next: recursive self-improvement, or RSI. This is the idea that AI systems are increasingly being used to build better AI systems, creating a feedback loop that could accelerate the very curves I showed you above. At Davos in January, Anthropic’s Dario Amodei explained that if you make models that are good at coding and good at AI research, you can use them to build the next generation of models, speeding up the loop. He noted that engineers within Anthropic barely write code themselves anymore. When OpenAI released its latest Codex model in February, the company stated it was “our first model that was instrumental in creating itself.” And Google DeepMind’s Demis Hassabis acknowledged at the same Davos panel that closing the self-improvement loop is something all the major labs are actively working on, even as he warned there are still missing capabilities and real risks.

We don’t know how far this goes. RSI has been a theoretical concept for decades, and the labs may hit bottlenecks, whether in compute, in data, or in the sheer difficulty of AI research. We also don’t know whether LLM-based AIs will eventually hit a ceiling where they cannot get any better, or where the jagged frontier never smooths out. I don’t think we know anything for certain, but I also think we are past the point where recursive self-improvement is science fiction. Instead, it is an explicit item on the roadmap of every major AI company. If the loop does close, the exponential curves we’ve been watching would get steeper, with an uncertain endpoint.

So here is where we are today: the instability of that single week in February was a preview of what it feels like when the increasing ability of AI starts to interact with markets, jobs, and governments all at once. That feeling of uncertainty will likely only spread further. But uncertainty is not the same as helplessness. When a technology is this powerful and this unsettled, the choices that individuals and organizations make right now matter more. We can see the shape of the Thing now, but we can still influence the Thing itself, and what it means for all of us. We clearly don’t have rules or role models for how AI gets used at work, in schools, or in government. That’s a problem, but it also means that every organization figuring out a good way to use AI right now is setting a precedent for everyone else. The window to shape the Thing may not last long, but it is here now.

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I have written eight of these guides since ChatGPT came out, but this version represents a very large break with the past, because what it means to “use AI” has changed dramatically. Until a few months ago, for the vast majority of people, “using AI” meant talking to a chatbot in a back-and-forth conversation. But over the past few months, it has become practical to use AI as an agent: you can assign them to a task and they do them, using tools as appropriate. Because of this change, you have to consider three things when deciding what AI to use: Models, Apps, and Harnesses.

Models are the underlying AI brains, and the big three are GPT-5.2/5.3, Claude Opus 4.6, and Gemini 3 Pro (the companies are releasing new models much more rapidly than the past, so version numbers may change in the coming weeks). These are what determine how smart the system is, how well it reasons, how good it is at writing or coding or analyzing a spreadsheet, and how well it can see images or create them. Models are what the benchmarks measure and what the AI companies race to improve. When people say “Claude is better at writing” or “ChatGPT is better at math,” they’re talking about models.

Apps are the products you actually use to talk to a model, and which let models do real work for you. The most common app is the website for each of these models: chatgpt.com, claude.ai, gemini.google.com (or else their equivalent application on your phone). Increasingly, there are other apps made by each of these AI companies as well, including coding tools like OpenAI Codex or Claude Code, and desktop tools like Claude Cowork.

Harnesses are what let the power of AI models do real work, like a horse harness takes the raw power of the horse and lets it pull a cart or plow. A harness is a system that lets the AI use tools, take actions, and complete multi-step tasks on its own. Apps come with a harness. Claude on the website has a harness that lets Claude 4.6 Opus do web searches and write code but also has instructions about how to approach various problems like creating spreadsheets or doing graphic design work. Claude Code has an even more extensive harness: it gives Claude 4.6 Opus a virtual computer, a web browser, a code terminal, and the ability to string these together to actually do stuff like researching, building, and testing your new website from scratch. Manus (recently acquired by Meta) was essentially a standalone harness that could wrap around multiple models. OpenClaw, which made big news recently, is mostly a harness that allows you to use any AI model locally on your computer.

Until recently, you didn’t have to know this. The model was the product, the app was the website, and the harness was minimal. You typed, it responded, you typed again. Now the same model can behave very differently depending on what harness it’s operating in. Claude Opus 4.6 talking to you in a chat window is a very different experience from Claude Opus 4.6 operating inside Claude Code, autonomously writing and testing software for hours at a stretch. GPT-5.2 answering a question is a very different experience from GPT-5.2 Thinking navigating websites and building you a slide deck.

It means that the question “which AI should I use?” has gotten harder to answer, because the answer now depends on what you’re trying to do with it. So let me walk through the landscape.

The Models Right Now

The top models are remarkably close in overall capability and are generally “smarter” and make fewer errors than ever. But, if you want to use an advanced AI seriously, you’ll need to pay at least $20 a month (though some areas of the world have alternate plans that charge less). Those $20 get you two things: a choice of which model to use and the ability to use the more advanced frontier models and apps. I wish I could tell you the free models currently available are as good as the paid models, but they are not. The free models are all optimized for chat, rather than accuracy, so they are very fast and often more fun to talk to, but much less accurate and capable. Often, when someone posts an example of an AI doing something stupid, it is because they are either using the free models or because they have not selected a smarter model to work with.

The big three frontier models are Claude Opus 4.6 from Anthropic, Google’s Gemini 3.0 Pro, and OpenAI’s ChatGPT 5.2 Thinking. With all of the options, you get access to top-of-the-line AI models with a voice mode, the ability to see images and documents, the ability to execute code, good mobile apps, and the ability to create images and video (Claude lacks here, however). They all have different personalities and strengths and weaknesses, but for most people, just selecting the one they like best will suffice. For now, the other companies in this space have fallen behind, whether in models or in apps and harnesses, though some users may still have reasons for picking them.

When you are using any AI app (more on those shortly), including phone apps or websites, the single most important thing you can do is pick the right model, which the AI companies do not make easy. If you are just chatting, the default models are fine, if you want to do real work, they are not. For ChatGPT, no matter whether you use the free or pay version, the default model you are given is “ChatGPT 5.2”. The issue is that GPT-5.2 is not one model, it is many, from the very weak GPT-5.2 mini to the very good GPT-5.2 Thinking to the extremely powerful GPT-5.2 Pro. When you select GPT-5.2, what you are really getting is “auto” mode, where the AI decides which model to use, often a less powerful one. By paying, you get to decide which model to use, and, to further complicate things, you can also select how hard the model “thinks” about the answer. For anything complex, I always manually select GPT-5.2 Thinking Extended (on the $20 plan) or GPT-5.2 Thinking Heavy (on more expensive plans). For a really hard problem that requires a lot of thinking, you can pick GPT-5.2 Pro, the strongest model, which is only available at a higher cost tier.

For Gemini, there are three options: Gemini 3 Flash, Gemini 3 Thinking, and, for some paid plans, 3 Pro. If you pay for the Ultra plan, you get access to Gemini Deep Think for very hard problems (which is in another menu entirely). Always pick Gemini 3 Pro or Thinking for any serious problem. For Claude, you need to pick Opus 4.6 (though the new Sonnet 4.6 is also powerful, it is not quite as good) and turn on the “extended thinking” switch.

Again, for most people, the model differences are now small enough that the app and harness matter more than the model. Which brings us to the bigger question.

The Chatbot Interfaces

The vast majority of people use chatbots, the main websites or mobile apps of ChatGPT, Claude, and Gemini, to access their AI models. In fact, we can call the chatbot the most important and widespread AI app. In the past few months, these apps have become quite different from each other.

Some of the differences are which features are bundled with AI:

• Bundled into the Gemini chatbot (and accessible with the little plus button): you can access nano banana (the best current AI image creation tool), Veo 3.1 (a leading AI video creation tool), Guided Learning (when trying to study, this helps the AI act more like a tutor), and Deep Research

• Bundled into ChatGPT is even more of a hodgepodge of options accessible with the plus button. You can Create Images (the image generator is almost as good as nano banana, but you can’t access the Sora video creator through the chatbot), Study and Learn (the equivalent to Guided Learning in Gemini, but there is also a separate Quizzes creator for some reason), Deep Research and Shopping Research (surprisingly good and overlooked), and a set of other options that most people will not use often, so I won’t cover here.

• Claude has only Deep Research as bundled option, but you can access a study mode by creating a Project and selecting study project.

• All of the AI models let you connect to data, such as letting the AI read your email and calendar, access your files, or connect to other applications. This can make AI far more useful, but, again, each AI tool has a different set of connectors you can use.

These are confusing! For most people doing real work, the most important additional feature is Deep Research and connecting AI to your content, but you may want to experiment with the others. Increasingly, however, what matters is the harness - the tools the AI has access to. And here, OpenAI and Anthropic have clear leads over Google. Both Claude.ai and ChatGPT have the ability to write and execute code, give you files, do extensive research, and a lot more. Google’s Gemini website is much less capable (even though its AI model is just as good),

As you can see, asking a similar question gets working spreadsheets and PowerPoints from ChatGPT and Claude, along with clear citations I can follow up on. Gemini, however, is unable to produce either kind of document, and it does not provide citations or research. I do expect that Google will catch up here soon, however.

One final note on Chatbots. GPT-5.2 Pro, with the harness that comes with it, is a VERY smart model. It is the model that just helped derive a novel result in physics and it is the one I find most capable of doing complex statistical and analytical work. It is only accessible through more expensive plans. Google Gemini 3 Deep Think also seems very capable, but suffers from the same harness problem.

Other apps and harnesses

The chatbot websites are where most people interact with AI, but they are increasingly not where the most impressive work gets done. A growing set of other apps wrap these same models in more powerful harnesses, and they matter.

Claude Code, OpenAI Codex, and Google Antigravity are the most well-developed of these, and they are all aimed at coders. Each of them gives an AI model access to your codebase, a terminal, and the ability to write, run, and test code on its own. You describe what you want built and the AI goes and builds it, coming back when it’s done or stuck. If you write code for a living, these tools are changing your job. Because they have the most extensive harnesses, even if you don’t code, they can still do a tremendous amount.

For example, a couple years ago, I became interested in how you would make an entirely paper-based LLM by providing all of the original GPT-1’s internal weights and parameters (the code of the AI, listed as 117 million numbers) in a set of books. In theory, with enough time, you could use those numbers to do the math of an AI by hand. This seemed like a fun idea, but obviously not worth doing. A week ago, I asked Claude Code to just do it for me. Over the course of an hour or so (mostly the AI working, with a couple suggestions), it made 80 beautifully laid out volumes containing all of GPT-1, along with a guide to the math. It also came up with, and executed, covers for each volume that visualized the interior weights. It then put together a very elegant website (including the animation below), hooked it up to Stripe for payment and Lulu to print on demand, tested the whole thing, and launched it for me. I never touched or looked at any code. I had it make 20 books available at cost to see what happened - and sold out the same day. All of the volumes are still available as free PDFs on the site. Now, I can have a little project idea that would have required a lot of work, and just have it executed for me with very little effort on my part.

But the coding harnesses remain risky for amateurs and, obviously, focused on coding. New apps and harnesses are starting to focus on other types of knowledge work.

Claude for Excel and Powerpoint are examples of specific harnesses inside of applications. Both of them provide very impressive extensions to these programs. Claude for Excel, in particular, feels like a massive change in working with spreadsheets, with the potential for a similar impact to Claude Code for those who work with Excel for a living - you can, increasingly, tell the AI what you want to do and it acts a sort of junior analyst and does the work. Because the results are in Excel, they are easy to check. Google has some integration with Google Sheets (but not as deeply) and OpenAI does not really have an equivalent product.

Claude Cowork is something genuinely new, and it deserves its own category. Released by Anthropic in January, Cowork is essentially Claude Code for non-technical work. It runs on your desktop and can work directly with your local files and your browser. However, it is much more secure than Claude Code and less dangerous for non-technical users (it runs in a VM with default-deny networking and hard isolation baked in, for those who care about the details) You describe an outcome (organize these expense reports, pull data from these PDFs into a spreadsheet, draft a summary) and Claude makes a plan, breaks it into subtasks, and executes them on your computer while you watch (or don’t). It was built on the same agentic architecture as Claude Code, and was itself largely built by Claude Code in about two weeks. Neither OpenAI or Google have a direct equivalent, at least this week. Cowork is still a research preview, meaning it’s early and will eat through your usage limits fast, but it is a clear sign of where all of this is heading: AI that doesn’t just talk to you about your work, but does your work.

NotebookLM is Google’s answer to a different problem: how do you use AI to make sense of a lot of information? You can ask NotebookLM to do its own deep research, or else add in your own papers, YouTube videos, websites, or files, and NotebookLM builds an interactive knowledge base you can query, turn into slides, mind maps, videos and, most famously, AI-generated podcasts where two hosts discuss your material (you can even interrupt the hosts to ask questions). If you are a student, a researcher, or anyone who regularly needs to make sense of a pile of documents, NotebookLM is a very useful tool..

And then there is OpenClaw, which I want to mention even though it doesn’t fit neatly into any of these categories and which you almost definitely shouldn’t use. OpenClaw is an open-source AI agent that went viral in late January. It runs locally on your computer, connects to whatever AI model you want, and you talk to it like you were chatting with a person using standard chats like WhatsApp or iMessage. It can browse the web, manage your files, send emails, and run commands. It is sort of a 24/7 personal assistant that lives on your machine. It is also a serious security risk: you are giving an AI broad access to your computer and your accounts, and no one knows exactly what dangers you are exposing yourself to. But it does serve as a sign of where things are going.

What to do now

I know this is a lot. Let me simplify.

If you are just getting started, pick one of the three systems (ChatGPT, Claude, or Gemini), pay the $20, and select the advanced model. The advice from my book still holds: invite AI to everything you do. Start using it for real work. Upload a document you’re actually working on. Give the AI a very complex task in the form of an RFP or SOP. Have a back-and-forth conversation and push it. This alone will teach you more than any guide.

If you are already comfortable with chatbots, try the specific apps. NotebookLM is free and easy to use, which makes it a good starting place. If you want to go deeper, Anthropic offers the most powerful package in Claude Code, Claude Cowork (both accessible through Claude Desktop) as well as the specialized PowerPoint and Excel Plugins. Give them a try. Again, not as a demo, but with something you actually need done. Watch what it does. Steer it when it goes wrong. You aren’t prompting, you are (as I wrote in my last piece) managing.

The shift from chatbot to agent is the most important change in how people use AI since ChatGPT launched. It is still early, and these tools are still hard to figure out and will still do baffling things. But an AI that does things is fundamentally more useful than an AI that says things, and learning to use it that way is worth your time.

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Claude Opus 4.8: “a modest but tangible improvement” 28th May 2026 Anthropic shipped Claude Opus 4.8 today. My favourite thing about it is this note in the release announcement: Users will find Opus 4.8 to be a modest but tangible improvement on its predecessor. There’s still more to be done: we’re working on developing and releasing models that provide many of the same capabilities as Opus at a lower cost. It’s so refreshing to see an AI lab honestly describe a release as a minor incremental improvement over the previous model! Honesty seems to be a theme. Here’s my other favorite note from that announcement: One of the most prominent improvements in Opus 4.8 is its honesty. We train all our models to be honest---for instance, to avoid making claims that they can’t support. But a general problem with AI models is that they sometimes jump to conclusions, confidently claiming to have made progress in their work despite the evidence being thin. Early testers report that Opus 4.8 is more likely to flag uncertainties about its work and less likely to make unsupported claims. This is borne out in our evaluations, which show that Opus 4.8 is around four times less likely than its predecessor to allow flaws in code it has written to pass unremarked. That linked system card includes the following: Claude Opus 4.8 had the lowest incorrect-rate of the six models on every benchmark—the most direct measure of factual hallucination. It achieved this mainly by abstaining on questions about which it was uncertain rather than by answering more questions correctly. Model characteristics Not much has changed since 4.7. It’s priced the same as Opus 4.5/4.6/4.7—$5/million input and $25 per million output. “Fast mode” is twice that price, which is a significant reduction from their previous models—fast mode on 4.6/4.7 remains at $30/$150. Note that fast mode is only available to organizations that are part of the research preview, “Contact your account manager to request access”. Both the reliable knowledge cutoff and the training data cutoff are January 2026, the same as for 4.7. The context window is still 1,000,000 tokens, and the max output is 128,000 tokens. The What’s new in Claude Opus 4.8 document has some of the more interesting details. These caught my eye: Mid-conversation system messages. Claude Opus 4.8 accepts role: "system" messages immediately after a user turn in themessages array (subject to placement rules). This lets you append updated instructions later in a long-running conversation without restating the full system prompt, which preserves prompt cache hits on the earlier turns and reduces input cost on agentic loops. See also this update to the Anthropic Python SDK. Being able to steer the system prompt mid-conversation sounds really powerful. I was worried this would be incompatible with the abstraction provided by my own LLM library, which expects a single system prompt per conversation... but it turns out my recent redesign should handle that just fine. Lower prompt cache minimum. The minimum cacheable prompt length on Claude Opus 4.8 is 1,024 tokens, lower than on Claude Opus 4.7. I checked and 4.7’s minimum was 4,096. And some pelicans Here are pelicans riding bicycles for all five thinking levels, low , medium , high , xhigh , and max : This time I ran them using the LLM CLI, exported the logs to Markdown and then had Claude Opus 4.8 build me an HTML tool that could render that Markdown with the svg fenced code blocks displayed as SVGs on the page. (I later had GPT-5.5 xhigh in Codex update that code to remove any XSS holes. I’m sure Claude could have done that if I’d asked, but GPT-5.5 is my code security blanket at the moment.) The max one was clearly the best, but it did take 25 input, 17,167 output tokens for a total cost of 43 cents! More recent articles - Running Python code in a sandbox with MicroPython and WASM - 6th June 2026 - I think Anthropic and OpenAI have found product-market fit - 27th May 2026