Anthropic releases its first Mythos-class model Claude Fable
Fable 5 is the first public release from the company's new Mythos class, a tier the company had held back over fears it was too dangerous to share. Anthropic says the public launch became possible because of new safeguards that block responses in cybersecurity, biology, chemistry, and a few other high-risk areas, sending those flagged queries to the older Opus 4.8 model instead.
Key Takeaways
- It says new safeguards make it possible to release a Mythos-class model it previously said was too risky to make public.
News AI Anthropic Anthropic releases its first Mythos-class model Claude Fable It says new safeguards make it possible to release a Mythos-class model it previously said was too risky to make public.
- Anthropic just announced Claude Fable 5, a new AI model it said is the most powerful model it has ever made widely available.
According to the company, Fable 5 "shows exceptional performance in software engineering, knowledge work, and vision," with its lead over other models growing as tasks become longer and more complex.
- Anthropic singled out cybersecurity and biology as two domains where the safeguards may block responses, both areas widely considered sensitive topics for advanced AI systems.
The company said that in testing, 95 percent of Fable sessions ran entirely on Fable responses, without falling back to Opus 4.8.
- For now, access appears limited to the steadily expanding group of organizations granted access to Claude Mythos Preview through Anthropic's - not entirely watertight - private Project Glasswing 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."
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Stats & Key Facts
- #Anthropic released Claude Fable 5 on June 9, 2026, calling it the most capable model it has ever made widely available.
- #Pricing for both models is significantly higher than its former flagship model - double rates for Claude Opus 4.8, though it's half what users pay for Mythos Preview - at $10 per million input tokens and $50 per million output tokens, Anthropic said.
It says new safeguards make it possible to release a Mythos-class model it previously said was too risky to make public. News AI Anthropic Anthropic releases its first Mythos-class model Claude Fable It says new safeguards make it possible to release a Mythos-class model it previously said was too risky to make public. It says new safeguards make it possible to release a Mythos-class model it previously said was too risky to make public.
by Robert Hart Jun 9, 2026, 5:00 PM UTC Link Share Gift Image: The Verge Robert Hart is a London-based reporter at The Verge covering all things AI and a Senior Tarbell Fellow. Previously, he wrote about health, science and tech for Forbes . Anthropic just announced Claude Fable 5, a new AI model it said is the most powerful model it has ever made widely available.
According to the company, Fable 5 "shows exceptional performance in software engineering, knowledge work, and vision," with its lead over other models growing as tasks become longer and more complex. Fable 5 marks the first broad release from Anthropic's Mythos class of AI models, after the company said the family was so capable at cybersecurity tasks that it was too dangerous to release publicly . Anthropic said the release was "made possible by new safeguards that block responses in specific high-risk areas," with the system falling back to Claude Opus 4.8 - a model it praised for "honesty" when it launched last month.
For more details please read the original article at The Verge AI.
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