Anthropic launches its first Mythos Claude Fable model

Anthropic has just announced Claude Fable 5, a new AI model that it says is the most powerful model it has ever made widely available.

According to the company, Fable 5 “demonstrates exceptional performance in software engineering, cognitive work, and vision,” with its outperformance over other models increasingly as tasks become longer and more complex.

Fable 5 marks the first large-scale release of Anthropic’s Mythos class of AI models, after the company said the family was so capable of taking on cybersecurity tasks that it was. Too dangerous to be published publicly. Anthropic said the release was “made possible by new safeguards that prevent responses in specific high-risk areas”, with the system reverting to Cloud Opus 4.8 – a model He praised for “Honesty” when it was released last month.

Anthropic singled out cybersecurity and biology as two areas where safeguards may prevent responses, both areas widely considered sensitive topics for advanced AI systems. During testing, 95 percent of Fable sessions were executed entirely using Fable Responses, without downgrading to Opus 4.8, the company said.

The company is also releasing Claude Mythos 5, but has provided few details on what that means. In a blog post, Anthropic said that Mythos 5 is the same basic model as Fable 5, “but with safeguards lifted in some areas.” For now, access appears increasingly limited Expanded set of organizations that have been granted access To preview Claude Mythos via Anthropic — Not completely watertight – private Glasswing Project Initiative. Those users will be able to upgrade to Mythos 5, Anthropic said, adding that it plans to “expand access over time through a more systematic trusted access program.”

Anthropic did not respond on record EdgeRequested comment explaining how either model relates to the Claude Mythos Preview or why the models are numbered “5” when there don’t appear to be any previously released Mythos or Fable models.

The price of both models is much higher than the previous flagship model — double Pricing for Claude Opus 4.8, though half what users pay for Mythos Preview — is $10 per million input tokens and $50 per million output tokens, Anthropic said.