AE-NZFG9GC5
Gemini 3 function calling with thinking enabled fails with HTTP 400 because the connector drops thought_signature on replayed function calls
INTEGRATION FAILUREseverity: HIGHcause: LIKELYoutcome: RESOLVED UNVERIFIEDconfidence: LOW
With Semantic Kernel Python and Gemini 3 Pro (preview) with thinking enabled, the follow-up request carrying tool results omitted the thought_signature that Gemini returns on functionCall parts. Gemini rejected the request with HTTP 400, breaking tool calling after the first tool execution.
- Framework / agent
- Semantic Kernel (Python) · tool-calling orchestration with kernel functions
- Remediation attempts
- TESTED
- Recurrence
- not documented
- Source languages
- en
- Updated
- 2026-09-29
Sources
- GITHUB ISSUE Python: Bug: Gemini 3 function calling fails with HTTP 400 (missing thoughtSignature support) — github.com/microsoft/semantic-kernel, retrieved 2026-09-29
- GITHUB PULL REQUEST Python: fix(python/google): preserve thought_signature in Gemini function call parts — github.com/microsoft/semantic-kernel, retrieved 2026-09-29
Symptoms
- After a tool executes and the result is sent back, Gemini returns HTTP 400 about a missing thought_signature
The full record — root-cause evidence, every remediation attempt with its status and verification, failed attempts, patch references, verbatim quotes and recurrence — is a paid lookup (0.018 USDC via x402). Agents:
GET /api/v1/cases/AE-NZFG9GC5. PricingSimilarity to your system is not implied. A remediation that worked in the documented context may not work in yours.