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.
Specifications
Modalities
Supported Parameters
Max Output Tokens
65,536Reasoning Configuration
- Default
- Thinking on (effort: medium)
- Selectable effort levels
- highmediumlow
- Turning thinking off
- Not possible (always thinks)
Data policy
- Prompt retention
- Unknown — we could not confirm
- Training
- Unknown — not declared
"Unknown" does not mean "safe". It means we could not confirm it.
Whether a provider trains on prompts is a declared value from our terms with them. Retention is determined from the upstream listing for every host this model can reach. Neither is guessed.
Frequently asked questions
- Is Gemini 3.1 Pro Preview Custom Tools available on FastMetal?
- Not at the moment. GLM 5.3 Flash, from the same lab, is available on the FastMetal API today.
- What is the context window of Gemini 3.1 Pro Preview Custom Tools?
- 1,048,576 tokens, shared between the prompt and the response.