Anthropic Launches Claude Fable 5.1 & Mythos 5.1: Features & Pricing
Anthropic has introduced Claude Fable 5.1 and Claude Mythos 5.1, marking another significant step in the evolution of its frontier AI models. While both models are built on the same underlying architecture, they are designed for different audiences through distinct safety controls. Claude Fable 5.1 is broadly available for developers, enterprises, and paid Claude users, whereas Claude Mythos 5.1 is reserved for vetted organizations working on advanced cybersecurity and life sciences projects. Beyond performance improvements, Anthropic has focused on making long-running AI workloads more efficient by significantly lowering prompt cache-read costs. The biggest upgrades in Claude Fable 5.1 revolve around extended coding sessions, autonomous agentic workflows, and complex knowledge tasks. The model can work across entire codebases, perform code reviews, generate and verify tests, identify root causes instead of temporary fixes, and interpret charts, tables, and diagrams within docume...