Tool System

Deep dive into Claude Code’s tool description design: how to help AI accurately understand each tool’s purpose and use cases. Unveiling how tool descriptions become “instructions for the model,” how inputSchema affects parameter selection, and the application of dynamic descriptions.

Deep dive into Claude Code’s tool system: how 40+ tools form an extensible capability architecture through unified interface contracts, three-tier filtering pipelines, and fail-closed defaults. From Tool.ts interface to buildTool factory, revealing the underlying mechanisms of AI tool calling.