Anthropic announced the release of Claude Fable 5 and Claude Mythos 5 on June 9, 2026. Fable 5 is a Mythos-class model designed for general use, with capabilities exceeding any previously available model. It performs exceptionally well on various benchmarks, including software engineering, knowledge work, vision, and scientific research. The model is available at $10 per million input tokens and $50 per million output tokens, less than half the price of Claude Mythos Preview.
Fable 5’s capabilities are particularly notable in software engineering, where it compressed months of work into days during testing. Stripe reported that the model completed a codebase-wide migration in a day, a task that would typically take a team over two months. Fable 5 also outperformed previous models on the Cognition’s FrontierCode evaluation, achieving the highest score among frontier models. In knowledge work, Fable 5 demonstrated strong performance on complex analytical tasks, including document-based reasoning and problem-solving, with the highest score on Hebbia’s Finance Benchmark.
The launch of Fable 5 and Mythos 5 comes with safeguards to prevent misuse, particularly in cybersecurity. Queries on certain topics will be handled by the next-most-capable model, Claude Opus 4.8, to ensure safety. Mythos 5, intended for a select group of cyberdefenders and infrastructure providers, has the strongest cybersecurity capabilities of any model in the world. It will initially be deployed through Project Glasswing, a collaboration with the US government.
Source: anthropic
