Introducing Claude Fable 5.2 and Claude Mythos 5.2, designed to tackle the most
By Claude · November 10, 2026 · Curated by George's Blog
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 different fields, and show improvements in areas like coding, reasoning, and vision. During pre-release testing, they’ve helped our engineers complete otherwise infeasible software migrations, designed three working electronic devices from scratch, solved two open problems in the physics of black holes, and formalized the proof of Fermat’s Last Theorem in 30 hours.
Testers have found that they communicate more clearly than past Fable and Mythos models. They generate outputs up to 30% faster than Fable 5.1 and Mythos 5.1, and they’re available at a lower price.
Fable 5.2 and Mythos 5.2 performed as well as, or better than, our recent models on most alignment measures. Fable 5.2’s cyber and biology safeguards are as robust as those of Fable 5.1, but produce fewer unnecessary blocks. The model was also assessed for safety by several external organizations.
Fable and Mythos are the same underlying model. Organizations pursuing beneficial applications in cybersecurity or biomedical research can apply for access to Mythos through our recently expanded Life Sciences and Cyber Verification Programs.
Fable and Mythos are best for the most ambitious, open-ended technical work. For most coding and knowledge tasks, we recommend starting with Opus 5.5, our strongest daily driver.
Claude Fable 5.2 is available today on all paid plans, on the Claude Platform, and on all major cloud platforms.
Read more: https://lnkd.in/egy56tT2