Anthropic's Claude Fable 5.1 Cuts Costs by Up to 45 Percent for Agentic Work
Anthropic releases its newest AI models, Claude Fable 5.1 and Mythos 5.1, in response to customer criticism about pricing, data retention, and overly aggressive safeguards. The company claims Fable 5.1 delivers stronger performance than its predecessor while costing about 25 percent less on average and up to 45 percent less for complex agentic tasks, thanks to reduced pricing on cached data that has already been processed and stored. Mythos 5.1 is also launching in Project Glasswing.
Early impressions from business leaders are largely positive. Every CEO Dan Shipper calls it "the strongest coding model we've used" and praises it as fast, token-efficient, and able to speak naturally. Box CEO Aaron Levie reports that an agent running Fable 5.1 catches subtleties and ambiguities in data that Fable 5 misses in the same tests. Reviewer Lisan al Gaib notes that Mythos 5.1 with low reasoning settings matches the previous model running at Max reasoning on benchmarks.
Anthropic also addresses safety and privacy concerns with the release. Fable 5.1 includes more precise safeguards that are less likely to block basic biology questions, though Mythos 5.1 keeps the same biology restrictions as before. On data retention, Anthropic says its Enterprise Frontier Safeguards offer complete privacy by storing data on the customer's own infrastructure.