Fast mode for Claude Opus 5.5 is out of research preview: the fast-mode-2026-02-01 beta header is no longer required (though still accepted), and the model now has a default fast mode rate limit in every usage tier. Fast mode for Claude Opus 5 and Claude Opus 4.8 remains in research preview and still requires the beta header.
Read the full story on platform.claude.com
What to doRemove the fast-mode beta header from Claude Opus 5.5 requests if you no longer need it, but keep sending it for Claude Opus 5 and Claude Opus 4.8 fast mode requests.
- Provider
- Anthropic
- Source
- platform.claude.com