Anthropic on Tuesday launched Fable 5, a Mythos-class model it says is safe for general use and more capable than any model it has ever made widely available. The company also released Mythos 5 for a small group of cyberdefenders and infrastructure providers, giving the two models different paths to the market on the same day.
That split matters because Fable 5 is now the default answer for people searching for Anthropic’s newest flagship, while Mythos 5 is being held back for users the company trusts to handle more sensitive work. Anthropic said both models are priced at $10 per million input tokens and $50 per million output tokens, less than half the price of Claude Mythos Preview, and that Fable 5 can already be used at scale by general customers.
The company said Fable 5 is state of the art across nearly all tested benchmarks of AI capability, with standout results in software engineering, knowledge work, vision and scientific research. It also said the model can work autonomously for longer than any previous Claude release. In early testing, Stripe reported that Fable 5 compressed months of engineering into days, including a codebase-wide migration completed in a day across a 50-million-line Ruby codebase that would otherwise have taken a whole team more than two months by hand.
Mythos 5 uses the same underlying model as Fable 5, but Anthropic said some safeguards are lifted so it can handle cybersecurity work more effectively. The company said it has the strongest cybersecurity capabilities of any model in the world and will initially deploy it through Project Glasswing in collaboration with the U.S. government as an upgrade to Claude Mythos Preview. Anthropic said the model’s capabilities could be misused to cause serious damage without safeguards, which is why access starts with a narrow group of cyberdefenders and infrastructure providers.
There is a catch in that design. Anthropic said its safeguards are conservative and can sometimes block harmless requests, even as the company is pushing the model out quickly. It said those safeguards trigger in less than 5% of sessions on average, and that some topics routed through Fable 5 will instead receive a response from Claude Opus 4.8. The company said it plans to expand access to Mythos 5 through a broader trusted access program, but did not say how many users will eventually be included.
That leaves Anthropic trying to do two things at once: put its most capable general model into wide use at a lower price, and keep its most powerful cybersecurity version inside a controlled channel. The first move will matter to everyday users and corporate customers now. The second will matter most to the defenders waiting to see how far Anthropic opens the gate.
