Gemini 3.1 Pro Preview Custom Tools

Gemini 3.1 Pro Preview Custom Tools is a variant of Gemini 3.1 Pro that improves tool selection behavior by preventing overuse of a general bash tool when more efficient third-party or user-defined functions are available. This specialized preview endpoint significantly increases function calling reliability and ensures the model selects the most appropriate tool in coding agents and complex, multi-tool workflows. It retains the core strengths of Gemini 3.1 Pro, including multimodal reasoning across text, image, video, audio, and code, a 1M-token context window, and strong software engineering performance.

Speech-to-textGoogle1M tokens$2.1801 / min

google/gemini-3.1-pro-preview-customtools

Context
1M tokens
Completion cap
65,536
Tools
Yes
JSON
Yes
Released
2026-02-25

Call it from Geek Hub

Same OpenAI SDK. Change the base URL and the model id.

curl https://api.geekhub.mx/v1/chat/completions \
  -H "Authorization: Bearer $GEEKHUB_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "google/gemini-3.1-pro-preview-customtools",
    "messages": [{"role": "user", "content": "Hola"}]
  }'
Get an API key

Frequently asked questions

What is Gemini 3.1 Pro Preview Custom Tools?
Gemini 3.1 Pro Preview Custom Tools is a variant of Gemini 3.1 Pro that improves tool selection behavior by preventing overuse of a general bash tool when more efficient third-party or user-defined functions are available. This specialized preview endpoint significantly increases function calling reliability and ensures the model selects the most appropriate tool in coding agents and complex, multi-tool workflows. It retains the core strengths of Gemini 3.1 Pro, including multimodal reasoning across text, image, video, audio, and code, a 1M-token context window, and strong software engineering performance. Gemini 3.1 Pro Preview Custom Tools runs on the Geek Hub API (OpenAI-compatible). Model id: google/gemini-3.1-pro-preview-customtools.
Is Gemini 3.1 Pro Preview Custom Tools free?
No. $2.1801 per minute on Geek Hub.
What is the context length of Gemini 3.1 Pro Preview Custom Tools?
Gemini 3.1 Pro Preview Custom Tools has a 1M tokens context window. It supports up to 65,536 completion tokens.
When was Gemini 3.1 Pro Preview Custom Tools released?
Gemini 3.1 Pro Preview Custom Tools was released on 2026-02-25.

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