Gemini 3.1 Pro Preview Custom Tools

Gemini 3.1 Pro Preview Custom Tools is a specialized variant of Google's Gemini 3.1 Pro designed to improve tool use in complex agentic workflows. It increases function-calling reliability and steers the model toward registered custom functions instead of defaulting to a generic bash tool, which makes it well suited to coding agents and multi-tool systems where the model must pick the right tool for each task. The variant belongs to the Gemini 3.1 Pro family of models, which succeeds earlier Gemini Pro generations, and is offered as a preview release that lets developers connect their own APIs and services to the underlying reasoning engine.

Beyond its tool-use focus, the model retains the broader Gemini 3.1 Pro capabilities that make it useful as a general assistant: multimodal understanding across text, images, video, audio, and code, strong reasoning over long inputs, and a that quick-info value window in the order of one million tokens for sustained multi-document workflows. Practical fit centers on building agents that orchestrate many custom tools and APIs, where consistent and accurate tool selection matters more than raw breadth, and on applications that combine bespoke integrations with translation, document reading, image understanding, and conversational dialogue. Teams that want the Gemini 3.1 Pro line's reasoning depth paired with disciplined, developer-controlled tool routing are the clearest audience for this preview variant.