OpenRouter Function Calling

Overview

OpenRouter supports OpenAI-compatible tool/function calling across multiple providers. Define tools as JSON Schema, send them with your request, and the model returns structured tool_calls instead of free text. This works with GPT-4o, Claude 3.5, Gemini, and other tool-capable models via the same API. The key difference from direct provider APIs: OpenRouter normalizes the tool calling interface, so the same code works across providers.

Prerequisites

• An OpenRouter API key (sk-or-v1-...) exported as OPENROUTER_API_KEY — see the openrouter-install-auth skill for setup
• Python 3.8+ or Node.js 18+ with the OpenAI SDK (pip install openai / npm install openai)
• A tool-capable model — check the Model Compatibility table below or query /api/v1/models (e.g., openai/gpt-4o, anthropic/claude-3.5-sonnet)
• Real function implementations to dispatch tool calls to (the execute_tool() dispatcher below stubs get_weather and search_database)

Instructions