Anthropic Launches Claude Fable 5, Its Most Capable AI Model for General Use
Anthropic has officially launched Claude Fable 5, describing it as the most capable AI model the company has ever made available to the general public. The release, announced on June 9, 2026, also includes Claude Mythos 5, a version of the same underlying model with certain safeguards lifted, reserved for a limited group of trusted partners.
Claude Fable 5 is described as state-of-the-art on nearly all tested AI capability benchmarks, with exceptional performance in software engineering, knowledge work, vision, scientific research, and other areas. Anthropic notes that the model’s advantages over previous versions grow significantly on longer and more complex tasks.
The launch comes with a notable safety layer baked in. Without safeguards, Fable 5’s capabilities in areas like cybersecurity could be misused to cause serious damage, so the model ships with classifiers that route certain sensitive queries to Claude Opus 4.8 instead. These classifiers are tuned conservatively and may occasionally catch harmless requests, but on average trigger in fewer than 5% of sessions.
In practical tests, the model’s performance has drawn strong feedback. Stripe reported that Claude Fable 5 compressed months of engineering work into days, completing a codebase-wide migration in a Ruby project spanning 50 million lines in a single day, a task that would have taken a full team over two months. On knowledge work, Fable 5 topped Hebbia’s Finance Benchmark for senior-level reasoning, with notable gains in document-based analysis, chart interpretation, and problem solving.
The vision capabilities of Claude Fable 5 are also a significant step forward. The model can extract precise figures from detailed scientific charts and rebuild a web application’s source code from screenshots alone, requiring far less scaffolding than earlier Claude versions.
Claude Mythos 5, the restricted counterpart, is being deployed through Project Glasswing in collaboration with the US government. It carries the same underlying model as Fable 5 but with cybersecurity safeguards lifted, and Anthropic says it holds the strongest cybersecurity capabilities of any AI model in the world. In life sciences, internal protein design experts used Mythos 5 to accelerate aspects of the drug design process by around ten times, with the model independently handling tasks normally completed by trained scientists across 14 protein targets.
On pricing, both models are offered at $10 per million input tokens and $50 per million output tokens, which is less than half the price of Claude Mythos Preview. Claude Fable 5 is available today on the Claude API using the model string claude-fable-5, and is included at no extra cost on Pro, Max, Team, and Enterprise plans through June 22, after which usage credits will be required.
Anthropic says it intends to expand access to Mythos 5 beyond current Glasswing partners through a broader trusted access program, including a dedicated pathway for biomedical researchers working in life sciences.
