On September 1, 2026 Anthropic unveiled Claude Fable 5.1, which costs about 25 percent less than the previous generation and cuts false security alerts for development teams by roughly 60 percent.
On September 1, 2026 Anthropic introduced two new models, Claude Fable 5.1 and Claude Mythos 5.1. According to the company's official announcement, Fable 5.1 is generally available through Anthropic's API, Amazon Bedrock, Google Cloud and Microsoft Foundry, while Mythos 5.1 is offered only through trusted-access programs for uses such as cybersecurity and life sciences.
The practically important point for technical teams is the pricing change: for typical workloads Fable 5.1 costs about 25 percent less than Fable 5, and cache-read cost drops 75 percent to $0.25 per million tokens — which directly affects the cost of running intelligent assistants and conversational tools at scale.
Anthropic also says Claude Code users see roughly 60 percent fewer false-positive cybersecurity alerts with this version — an improvement that can save significant time for security and DevSecOps teams struggling with high volumes of false alarms.
This release continues a trend in which model makers, instead of competing purely on model size, focus on lowering the cost per request and raising accuracy for specialized uses such as coding and security — good news for businesses looking for cost-effective AI in their products.
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