Claude Fable 5: The first Mythos model is powerful, expensive, and heavily filtered

Anthropic has launched Claude Fable 5, the first model in the new Mythos category. The model excels in most benchmarks, achieving 95% in the SWE-bench Verified standard, but it is priced at double that of the Opus 4.8 model, costing $10 or $50 per million tokens. The new model features strict safety filters that block approximately 9% of requests and a 30-day data retention policy that applies even to contracts that do not retain data. These changes reflect Anthropic's commitment to providing a secure and reliable model.