Anthropic Launches Claude Fable 5.1 with Up to 45% Cost Reduction for Agentic Work
New AI models address customer concerns about pricing, data retention, and content filtering while improving performance and token efficiency.
Anthropic has launched Claude Fable 5.1 and Mythos 5.1, addressing customer criticisms about price, data retention, and overzealous safeguards. The company claims Fable 5.1 offers stronger performance than its predecessor while reducing costs by approximately 25% in typical use cases and up to 45% for complex agentic tasks, thanks to reduced pricing on cached data that was already processed and stored.
Performance and Early User Feedback
Early impressions from users highlighted notable improvements. Every CEO Dan Shipper stated, "It's the strongest coding model we've used, but now it's fast, token-efficient, and crucially actually speaks like a normal person."
Box CEO Aaron Levie reported that his company's agent with Fable 5.1 picked up on subtleties and ambiguities in data that Fable 5 missed in the same test. Meanwhile, user Lisan al Gaib noted that on benchmarks, Mythos 5.1 with low reasoning scores the same as its predecessor set to Max reasoning.
Refined Safeguards and Cybersecurity Policy Updates
Fable 5.1 features "more precise safeguards" that Anthropic says are less likely to block basic biology questions than Fable 5. However, Mythos 5.1 retains the same biology restrictions as the previous model.
The company has also updated its cybersecurity policy, now allowing Fable 5.1 to be used for identifying software vulnerabilities. Anthropic will still redirect some cybersecurity tasks to Opus models, including penetration testing, exploit generation, and binary-based vulnerability scanning.
Data Retention and Privacy Controls
Addressing data retention concerns, Anthropic announced that Enterprise Frontier Safeguards offer "complete privacy" by storing data on the customer's cloud servers instead of its own infrastructure. This feature will start rolling out later this fall.
Availability
Claude Fable 5.1 is now available on all platforms, while Mythos 5.1 is available to Project Glasswing participants only.
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