claude-opus-5-5 returns 400 when disabled is passed; claude-sonnet-5-5 needs to switch to between_tools
Author’s note: this article is based on the Anthropic official docs dated 2026-11-08 (UTC+8) and the APIYI Claude thinking parameters guide updated at 10:40 on 2026-11-09, with all details fact-checked as of 2026-11-13. It’ll help you sidestep the 400 errors that claude-opus-5-5 and claude-sonnet-5-5 throw when you get the thinking parameter wrong. If you pass…