Input Formats & Examples

A tool description is the primary mechanism Claude uses to decide when and how to call a tool. Names alone don't carry enough signal. A strong description covers purpose, return values, edge cases, applicability boundaries, and crucially the input formats.

This lesson focuses on one high-leverage technique: showing concrete input examples so the model never has to guess what a parameter should look like.

Imagine a tool with a parameter called date. Is it 2026-06-10? 06/10/2026? June 10? A Unix timestamp? Without an example, Claude has to infer the format, and inference under ambiguity is where malformed tool calls come from.

An ambiguous schema doesn't fail loudly. It fails quietly, by producing inputs your backend rejects. Concrete examples remove that ambiguity at the source.