Anthropic launches Claude Fable 5.1 and says it’s up to 45 percent cheaper for agentic work — SkimNews
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- Anthropic launched Claude Fable 5.1 and Mythos 5.1, framing the release as a direct response to customer complaints about price, data retention, and overzealous safeguards.
- Fable 5.1 costs roughly 25% less than Fable 5 in typical use and up to 45% less for complex agentic tasks, driven by reduced pricing on cached, already-processed data.
- Every CEO Dan Shipper called Fable 5.1 "the strongest coding model we've used," highlighting token efficiency and natural-sounding outputs, while Box CEO Aaron Levie said its agent caught subtleties and ambiguities Fable 5 missed in the same test.
- Mythos 5.1 is available only through Project Glasswing, and benchmark work by Lisan al Gaib shows it matches its predecessor's Max-reasoning performance even when set to low reasoning.
- Fable 5.1 ships with more precise safeguards that Anthropic says are less likely to block basic biology questions, while Mythos 5.1 retains the previous model's biology restrictions.
- Enterprise Frontier Safeguards will offer "complete privacy" by storing customer data on the client's own cloud servers instead of Anthropic's, rolling out later this fall.
- Anthropic is now allowing Fable 5.1 to be used for identifying software vulnerabilities, but penetration testing, exploit generation, and binary-based vulnerability scanning will still be redirected to Opus models.
Why it matters: Anthropic is directly responding to enterprise pushback on three fronts—cost, data control, and safety over-blocking—by cutting agentic pricing up to 45% and letting customers keep inference data on their own servers. The narrower safeguard tuning on Fable 5.1 signals Anthropic is trying to keep biology and basic security use cases on-platform rather than driving them to less restrictive competitors, while still reserving the riskiest cybersecurity work for its top-tier Opus models.
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