Introducing Claude Fable 5.2 and Claude Mythos 5.2

Anthropic announced Claude Fable 5.2 and Claude Mythos 5.2, which share the same underlying model; Fable includes cybersecurity and biology safeguards for general availability, while Mythos is offered to vetted organizations through verification programs. The models improve on coding, reasoning, and vision, generate outputs up to 30% faster than version 5.1, and cost $8 per million input tokens and $40 per million output tokens, with an optional fast mode at $16/$80 that speeds generation up to 2.5 times. In prerelease testing they completed large software migrations, designed three working electronic devices, solved two open problems in black hole physics, made progress on robotics, and formalized Fermat's Last Theorem in 30 hours using 1,000 agents. Benchmark results show gains over Opus 5.5 across agentic coding, cybersecurity, protein design, computer use, robotics, and knowledge work. Safety testing found low risk from misalignment, fewer sandbox escape attempts than earlier models, reduced false-positive blocks, and the strongest anti-distillation protections to date. Fable 5.2 is available on AWS, Google Cloud, and Microsoft Azure, while Mythos 5.2 requires access through the Cyber and Life Sciences Verification Programs.

(Source：Anthropic)