hermes - 💡(How to fix) Fix [Bug]: Gemini Model missing thought_signature [8 comments, 7 participants]

You will get this error ❌ Non-retryable error (HTTP 400): HTTP 400: Gemini HTTP 400 (INVALID_ARGUMENT): Function call is missing a thought_signature in functionCall parts. This is required for tools to work correctly, and missing thought_signature may lead to degraded model performance. Additional data, function call default_api:skill_view , position 5. Please refer to https://ai.google.dev/gemini-api/docs/thought-signatures for more details. ❌ Non-retryable client error (HTTP 400). Aborting.

Additional Logs / Traceback (optional)

TL;DR

The error "Function call is missing a thought_signature in functionCall parts" suggests that the thought_signature parameter is required for the Gemini model to work correctly, and it's missing in the function call.

Guidance

• Review the Gemini API documentation at https://ai.google.dev/gemini-api/docs/thought-signatures to understand the requirements for the thought_signature parameter.
• Verify that the thought_signature is correctly configured in the Hermes Agent settings or function call parameters.
• Check the Hermes Agent version (v0.10.0) and ensure it's compatible with the Gemini model version (gemini-3.1-pro-preview).
• Investigate the default_api:skill_view function call at position 5, as mentioned in the error message, to determine why the thought_signature is missing.

Example

No code snippet is provided as the issue lacks specific code details.

Notes

The error message suggests a specific issue with the thought_signature parameter, but without more information about the code or configuration, it's difficult to provide a precise fix.

Recommendation

Apply workaround: Update the function call to include the required thought_signature parameter, as described in the Gemini API documentation, to resolve the error and ensure correct model performance.