Claude by Anthropic
A family of foundational AI models
5.0•1.1K reviews•99K followers
A family of foundational AI models
5.0•1.1K reviews•99K followers
We're an AI research company that builds reliable, interpretable, and steerable AI systems. Our first product is Claude, an AI assistant for tasks at any scale.
This is the 47th launch from Claude by Anthropic. View more
Claude Fable 5.2 and Mythos 5.2
Launching today
Claude Fable 5.2 and Mythos 5.2 are Anthropic’s upgraded frontier models for the hardest technical work. They are the same underlying model: Fable is open to all users, while Mythos, without some of Fable’s cyber and biology safeguards, goes to vetted organizations. Per Anthropic, outputs are up to 30% faster than 5.1 at a lower price ($8 input, $40 output per million tokens). Fable 5.2 scores 49.1% on FrontierCode 2.0, up from 32.4%. API ID: claude-fable-5-2.
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Launch tags:Artificial Intelligence
Launch Team
Render Sandboxes: a computer for every agentIsolated compute, persistent state and a real filesystem
Promoted
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Claude Fable 5.2 and Claude Mythos 5.2 are Anthropic’s new frontier models, built for the hardest technical work. Anthropic says they’re the same underlying model, with one difference in access. Fable has stronger cyber and biology safeguards, so it’s open to all users, while Mythos is available to vetted organizations through Anthropic’s Cyber Verification and Life Sciences Verification programs.
What’s new compared with 5.1:
Gains in coding, reasoning and vision, and clearer communication, according to testers
Outputs up to 30% faster, at a lower price
About 55% fewer unnecessary safeguard blocks (about 60% fewer in cybersecurity and 40% fewer in biology), with the same level of protection
Stronger protections against distillation (copying a model’s outputs to train another one)
On Anthropic’s own benchmarks, Fable 5.2 scores 49.1% on FrontierCode 2.0 (32.4% for Fable 5.1), 74.2% on Humanity’s Last Exam with tools (65.6%) and 41.3% on the Remote Labor Index (17.9%). It doesn’t lead everywhere. In the same table, Gemini 4 Carbon scores higher on AutomationBench (53.9% to 51.4%), Claude Opus 5.5 is slightly ahead on the AA-Briefcase Elo score (1800 to 1785), and at High effort on FrontierCode Fable matches Opus 5.5 at about half the cost per task. Anthropic itself suggests starting most coding and knowledge work on Opus 5.5 and moving up to Fable or Mythos for the most ambitious tasks.
Some pre-release results Anthropic highlights: three working electronic devices designed from scratch, a prototype operating system built by over 1,000 subagents over eight days, and Fermat’s Last Theorem formalized in Lean in 30 hours.
Pricing is $8 per million input tokens and $40 per million output tokens, with a fast mode that’s up to 2.5x faster at $16 and $80. The API ID is claude-fable-5-2, and it’s available on Claude.ai, Claude Code, AWS, Google Cloud and Azure. This week, eligible paid plans get a promotion that includes Fable for up to 50% of weekly usage limits on Pro and standard Team seats.
Good fit if you do long, complex coding, research or analysis work and want Anthropic’s most capable model. If you do security or life-sciences work, Mythos 5.2 is the version for vetted organizations.
Learn more: Anthropic’s announcement · System card · Models overview