Anthropic announced Claude Fable 5: a Mythos-class model made safe for general use, whose capabilities exceed any model they've previously made publicly available: https://www.anthropic.com/news/claude-fable-5-mythos-5 Here's what you need to know: What is it? Fable 5 is Anthropic's first Mythos-class model for general use, with safeguards that prevent everyday users from leveraging it for hacking infrastructure or accessing sensitive biological capabilities. Why the safeguards? Anthropic's Mythos Preview (revealed in April) proved particularly adept at finding vulnerabilities across every major operating system and web browser, raising concerns it could be used to break into critical infrastructure. Fable 5 addresses this by routing high-risk queries to the less capable Claude Opus 4.8 instead. Performance? It's state-of-the-art on nearly all tested benchmarks, showing exceptional performance in software engineering, knowledge work, vision, and scientific research — with the advantage growing larger on longer and more complex tasks. What about the full Mythos model? Anthropic is also launching Claude Mythos 5 for users who already had access to Mythos Preview through Project Glasswing, with fewer restrictions, deployed in collaboration with the U.S. Government for a small group of cyberdefenders and infrastructure providers. Availability? Fable 5 is available immediately, included on Pro, Max, Team, and Enterprise plans until June 22, 2026, after which usage credits may be required as capacity expands.