Turning thinking off on Claude Sonnet 5.5 fails with thinking type disabled, and computer_20251124 returns 400

Symptom

400 error when sending thinking: {"type":"disabled"} to claude-sonnet-5-5computer_20251124 tool rejected on Claude API or Google Cloudadvisor tool rejects Opus 4.8, Opus 4.7, or Sonnet 5 as the advisor model

Cause

Since the Claude Sonnet 5.5 launch on 2026-09-28, up-front thinking is turned off with thinking type between_tools instead of disabled, and only at high effort or below. The earlier computer_20251124 tool is not accepted on the Claude API and Google Cloud, and the advisor tool rejects some older models as advisors.

Fix

Send thinking type between_tools with effort high or lower. Switch to the computer_toolset_20260801 toolset. Pick a supported advisor model.

ApplyCopy

thinking: {"type": "between_tools"}, output_config: {"effort": "high"}

Affected

claude-sonnet-5-5, from 2026-09-28, migrating from Claude Sonnet 5

Sources

• https://platform.claude.com/docs/en/release-notes/overview
• https://platform.claude.com/docs/en/models/sonnet-5-5/migration-guide

Last verified 2026-10-17 · Confirmed by 0 builders