Anthropic launches Claude Fable 5.2 and Mythos 5.2

techNov 9, 2026129197

Anthropic released Claude Fable 5.2 and Claude Mythos 5.2, upgraded versions of its models aimed at hard technical work. Anthropic says both models generate outputs up to 30 percent faster than Fable 5.1 and Mythos 5.1 and are priced at 8 dollars per million input tokens and 40 dollars per million output tokens, with an optional fast mode that speeds generation up to 2.5 times for 16 dollars input and 80 dollars output per million tokens. In prerelease testing Anthropic reports the models helped engineers complete software migrations that would otherwise have been infeasible, designed three working electronic devices from scratch, solved two open problems in black hole physics, made progress on robotics evaluations, and formalized a proof of Fermat's Last Theorem in 30 hours. Anthropic says Fable and Mythos share the same underlying model but Fable includes stronger cybersecurity and biology safeguards and is available to all users while organizations seeking work in life sciences or cybersecurity must apply for Mythos access through Anthropic’s Life Sciences and Cyber Verification Programs. Anthropic reports extensive prerelease safety testing, says the models perform as well as or better than recent models on most alignment measures, and implemented protections against distillation attacks. Anthropic’s launch comes as the company prepares for a possible initial public offering as soon as next week.

mr. TIM

@timkellogg.me

Fable 5.2 - biggest improvement in knowledge work, robotics & scientific research - better at operating robots than most domain-specific AI models - math: formalized Fermat’s Last Theorem 100% where Opus 5.5 could only get 27% www.anthropic.com/claude-fable...

A performance comparison table titled "Claude Fable 5.2" evaluating different AI models (Fable 5.2, Fable 5.1, Opus 5.5, GPT-6 Astra, and Gemini 4 Carbon) across various benchmarks, including Agentic coding, Business workflows, Agentic scientific research, Cybersecurity, Protein design, Agentic search, Computer use, Robotics, Knowledge work, Multidisciplinary reasoning, and Visual chart recognition, with Fable 5.2 highlighted in a green column.

573d ago

mr. TIM12

note: it’s versioned “5.2” not “5.5” that means they thought there would be backlash if they called it a huge breakthrough (5.5 would’ve indicated a breakthrough) it’s clearly very good though. i suspect software engineers will still prefer Opus 5.5, but others may prefer Fable 5.2

Jms Dnns11

Fermat's Last Theorem as hello world

Dio2

> Testers have found that Fable 5.2 generate outputs up to 30% faster than Claude Fable 5.1 and Claude Mythos 5.1, and **they’re available at a lower price:** $8 per million input tokens and $40 per million output tokens.

Brian Ragle1

I'm reserving all comments about Fable until February so I can achieve maximum confusing references and double entendres. #iykyk

Quoting this

mr. TIM20

Fable 5.2 made real contributions to theoretical physics both of these are mathematical calculations that close some gnarly open problems. They aren’t particularly interesting on their own

Epoch AI

@epochai.bsky.social

Claude Fable 5.2 sets a new record on the Epoch Capabilities Index (ECI) at 174. The previous high was GPT-6 Astra’s 169. Fable 5.2’s score is above what the pre-Astra trend for reasoning models would have predicted.

343d ago

Anthropic {bot}

@anthropicai.xmirror.bot

Introducing Claude Fable 5.2 and Claude Mythos 5.2, designed to tackle the most daunting technical challenges. They’re capable collaborators on ambitious projects in many fields, and show improvements in areas like coding, reasoning, and vision.

313d ago

Quoting this

Anthropic {bot}28

Fable 5.2 is now available in the Claude Platform and Claude Code. It’s up to 30% faster than Fable 5.1, and costs $8/$40 per 1M tokens, down from $10/$50.

jeffery --dangerously-skip-permissions14

Oh interesting. I was 100% expecting Fable 5.5 to slot in to Anthropic's "5.5 models" product line. Weird. I wonder if *that* 5.5 is still coming.

Eris ⌬

@eriskii.net

New fable! It's better on stuff, robotics, etc blah blah, pricing updated to $8/40, prior was $10/50.

143d ago

Quoting this

austin (e/accordion 🪗)13

its crazy that in less than a year we've already achieved a "wait what iphone number are we up to?" release cadence

Eris ⌬13

also there is muse-tinyguy. so that's cool. I hope this one gets open weighted!

The Verge

@theverge.com

Claude Fable 5.2 is designed to take on big technical challenges, and it’s available today. www.theverge.com/ai-artificia...

133d ago

hikikomorphism

@hikikomorphism.bsky.social

but, like, professionally, because even if I'm not hugely impressed with the Claude model family (will probably be able to say why in a month or two), Fable 5.2 could be kinda fun to play with

103d ago

Tristan Gray

@eidyngray.scot

The incremental era of Anthropic continues, where even their own scoring shows improvements that barely shift the dial (especially in coding, which is most of their revenue) whilst getting more expensive. This won't light up the eyes of investors ahead of their IPO as confidence in AI crumbles.

claudeai
3h
In early testing on FrontierCode 2.0, Fable 5.2 at High effort scored about level with Opus 5.5 at Max effort, for roughly half the cost per task. At Xhigh effort, it scored the highest of any released model tested.
Medium is the default in Claude apps and Claude Code.
4
/
10

73d ago

Rollofthedice

@hotrollhottakes.bsky.social

My interest in future Claude models like Fable 5.2 atm extends mostly to whether they can actually express their points and topics in a direct, straightforward, and impactful manner. So far for me Gemini Argon blows everyone out of the water on this with GPT Astra at a decent second place.

53d ago

FinTwitter

@fintwitter.bsky.social

ANTHROPIC: CLAUDE FABLE 5.2 AND CLAUDE MYTHOS 5.2 ARE AVAILABLE NOW

3d ago

Noah Weinberger

@noahweinberger2003.bsky.social

The model that underlies Claude Fable 5.2 and Claude Mythos 5.2 is a step forward in general capabilities. However, during the model’s training, we took steps to limit advances in the specific research capabilities that could most directly accelerate AI development.

13d ago

Cryptovka | News | CryptoMarket & Blockchain

@cryptovka-news.bsky.social

Anthropic's Claude Fable 5.2 & Mythos 5.0 launch, generating complex software & physical designs. 🚀 Early users see big productivity gains, but high operational costs raise economic sustainability questions. Developers & startups ponder long-term viability as AI/DePIN sectors eye IPOs by 2027. 📈

23d ago

Theo - t3.gg {bot}

@theo.xmirror.bot

Wanted to try Fable 5.2 in it's native home (Claude Code desktop app). It's improved a lot, but holy SHIT the ux and navigation is horrible. Took me like 2 minutes just to add a project, even though I had the path on my clipboard? Had to dig through settings just to enable "bypass permissions"

🚨 Anthropic just released Claude Fable 5.2. Anthropic says it is up to 30% faster than Fable 5.1 and costs $8/$40 per 1M tokens, down from $10/$50. Can OpenAI match it on price?

13d ago

Climate, Ecology, War & More: Dr. Glen Barry BigEarthData.ai

@bigearthdata.ai

Anthropic launches Fable 5.2 and Mythos 5.2 with science, coding upgrades ->SiliconANGLE | More on "Anthropic releases advanced AI models" at BigEarthData.ai | #Anthropic #ArtificialIntelligence #Science

13d ago

3 sources

madrobot.blogAnthropic’s Claude Fable 5.2 is out, and it built a working operating system in eight days theverge.comAnthropic launches new Claude Fable and Mythos 5.2 models anthropic.comIntroducing Claude Fable 5.2 and Claude Mythos 5.2

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Anthropic launches Claude Fable 5.2 and Mythos 5.2

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