On June 9, 2026, Anthropic announced Claude Fable 5, a new Mythos-class model it describes as achieving state-of-the-art results on nearly all tested benchmarks, with particular strength in software engineering, knowledge work, vision, and scientific research. The company says Fable 5 scores highest among frontier models on Cognition’s FrontierCode evaluation and can work autonomously for longer than any previous Claude model, staying focused across millions of tokens in long-running tasks. Stripe is cited as reporting that Fable 5 compressed months of engineering into days on a Ruby codebase migration.
Pricing was set at 10 dollars per million input tokens and 50 dollars per million output tokens. Fable 5 was available immediately on the Claude API, with subscription-plan rollout running through June 22 before moving to usage credits.
Anthropic also announced Claude Mythos 5, the same underlying model with safety safeguards lifted, restricted initially to Project Glasswing partners and select researchers.