Anthropic launches Claude Fable 5.1 and Mythos 5.1

Anthropic released Claude Fable 5.1 as its generally available frontier model for coding and knowledge work, with Mythos 5.1 as the trusted-access variant for elevated cybersecurity and biology capabilities. The models share the same underlying weights; Fable applies more precise safeguards that reduce unnecessary biology refusals while blocking dual-use exploit generation. Pricing remains $10/$50 per million tokens with improved cache economics for agentic workloads.