Anthropic Releases Claude Fable 5.1 and Mythos 5.1

Anthropic announced the release of Claude Fable 5.1 and Claude Mythos 5.1, its most advanced AI models for coding and knowledge work.

“Claude Fable 5.1 and Claude Mythos 5.1 are the same model, but with different levels of safeguards,” Anthropic explains. “Fable 5.1 is generally available, while Mythos 5.1 is available only through our trusted access programs; its safeguards are specifically designed to support work in cybersecurity and the life sciences.”

According to the company, Fable 5.1 sets a new standard for coding, knowledge work, and long-running problem-solving tasks. It offers dramatically better performance than Fable 5 and achieves the same results at much lower costs. The model is smart enough to fix the root causes of software issues, Anthropic claims, while avoiding shortcuts that result in poorer-quality work.

Anthropic also says that its experiences with Fable and Mythos 5.1 are evidence that AI models will soon make important contributions to scientific discovery. The models include more precise safeguards for biology and cybersecurity, and they are compliant with the EU AI Act’s code of practice on transparency of AI-generated content and include watermarks and a detection API in private preview.

You can learn more on the Claude Platform Docs website.