Gemini 3.1 Pro Preview Custom Tools

This specialized preview variant of Gemini 3.1 Pro was engineered to address a specific weakness in tool-augmented workflows: the tendency to default to a general bash tool instead of selecting more efficient third-party or user-defined functions. By refining tool selection behavior, the model significantly increases function calling reliability, making it particularly valuable for coding agents that need to orchestrate multiple specialized tools without unnecessary detours. It retains the full multimodal reasoning capabilities of its base model, processing text, images, video, audio, and code inputs while producing structured text outputs, and maintains compatibility with the extended that quick-info value window that supports long-form reasoning across large codebases or documents.

The model has found strong adoption in production coding tools, including Kilo Code—an open-source AI coding agent integrated across VS Code, JetBrains, and CLI environments that has processed over 1.71 billion tokens through OpenRouter alone. This adoption signals that the tool-selection improvements translate into practical gains for real development workflows. Organizations deploying the model benefit from privacy-conscious routes offering zero data retention and GDPR compliance, making it suitable for enterprise coding agents and complex multi-tool automation without compromising on data handling standards. The variant strikes a balance between the flagship capabilities of Gemini 3.1 Pro and the operational precision required for reliable automated tool orchestration.