Anthropic Launches Claude Fable 5: A Mythos-Class Model Made Safe for General Use

What happened

Anthropic has launched Claude Fable 5, a Mythos-class model that surpasses all its previous releases on nearly every benchmark of AI capability. The model shows exceptional performance in software engineering, knowledge work, vision, and scientific research, with its lead over earlier Claude models growing wider the longer and more complex the task.

Why it matters

To release a model this capable safely, Anthropic tuned conservative safeguards that route sensitive queries to Claude Opus 4.8 instead. These safeguards trigger in fewer than 5% of sessions on average, though the company acknowledges they sometimes catch harmless requests. Alongside Fable 5, Anthropic launched Claude Mythos 5, the same underlying model with lifted restrictions, deployed through Project Glasswing in collaboration with the US government to help cyberdefenders secure critical infrastructure.

What's next

Priced at USD 10 per million input tokens and USD 50 per million output tokens, Fable 5 costs less than half of the previous Mythos Preview. Early testers including Stripe have already begun integrating the model. Anthropic says this joint launch is another step toward bringing advanced AI capabilities to as many users as possible, as quickly and as safely as it can.