Claude Fable 5.1 now available on AI Gateway
Claude Fable 5.1 from Anthropic is now available on AI Gateway.
Claude Fable 5.1 from Anthropic is now available on AI Gateway in Vercel. Its improvements over previous Claude models are concentrated in long, multi-stage work: agentic coding, knowledge work, and research that takes several rounds of searching and following up.
Anthropic ships Fable 5.1 with cybersecurity and biology safety classifiers enabled. Finding vulnerabilities in source code is allowed, but some routine coding and debugging may still be refused. To keep requests serviced when a classifier triggers, AI Gateway supports model fallbacks: add a models array to providerOptions.gateway, and the gateway works down the list in order, for example Opus 5 then Sonnet 5, until one succeeds. The same fallback option works across Chat Completions, Messages, and OpenAI Responses formats.
The model can also be connected to coding agents by running vercel ai-gateway coding-agents setup and selecting anthropic/claude-fable-5.1 inside agents such as Claude Code, Codex, OpenCode, Cursor, or Pi. Anthropic does not support Zero Data Retention for Fable 5.1: prompts and completions are retained for 30 days but are not used to train Claude.
