India, June 10 -- Artificial intelligence company Anthropic has introduced Claude Fable 5, a new AI system that the company describes as the first public release from its powerful Mythos class of models.

According to a report from The Verge, Microsoft has restricted employee access to Anthropic's newly launched Claude Fable 5, citing concerns around the model's data retention policies.

On SWE-Bench Pro, which evaluates real-world software engineering performance, Fable 5 achieved 80.3%, ahead of Claude Mythos Preview’s 77.8%, GPT 5.5’s 58.6%, and Gemini 3.5 Pro’s 54.2%.