Claude Fable 5 and Claude Mythos 5
Anthropic launched Claude Fable 5, its most capable publicly released model, rated Mythos-class. It achieves state-of-the-art on nearly all benchmarks, especially on long, complex tasks in software engineering, knowledge work, and vision. To mitigate misuse risks in cybersecurity and biology, Fable 5 ships with conservative safety classifiers that fall back to Opus 4.8 for sensitive queries, triggering in under 5% of sessions. Claude Mythos 5, the same model with safeguards lifted, is available to cyberdefenders and certain biologists. New 30-day business data retention is mandated for Mythos-class models. The post includes results from Stripe, Cognition, and internal protein design and genomics experiments. Pricing is $10/M input tokens and $50/M output tokens.