Claude Fable 5.1 & Claude Mythos 5.1

Claude Fable 5.1 and Claude Mythos 5.1 are Anthropic's most advanced large language models, optimized for complex coding, knowledge work, and agentic scientific research. While they share the same underlying architecture, Fable 5.1 is generally available for broad use, whereas Mythos 5.1 features specialized, permissive safeguards for cybersecurity and life sciences research.

Claude Fable 5.1 and Claude Mythos 5.1 are Anthropic's most advanced large language models, optimized for complex coding, knowledge work, and agentic scientific research. While they share the same underlying architecture, Fable 5.1 is generally available for broad use, whereas Mythos 5.1 features specialized, permissive safeguards for cybersecurity and life sciences research.

• 01Advanced agentic coding and long-horizon problem solving
• 0275% reduction in cache read pricing
• 03Enterprise Frontier Safeguards (EFS) for zero data retention
• 04Improved biology and cybersecurity safeguards with fewer false positives
• 05Multidisciplinary reasoning and scientific research capabilities