Kimi K3.1 Pro Models Reject Requests With Thinking Disabled

Kimi's K3.1 Pro models, identified as k3.1-pro and k3.1-pro-highspeed on Kimi Code, support only thinking mode (the built-in reasoning step), according to product documentation published 23 October 2026. Requests with thinking disabled are rejected. Integrators who toggled reasoning off per request must remove that parameter or expect errors.