The Art of Tool Description

A tool description should answer “when to use” not just “what it can do”.

Limitations (what the tool cannot do) are mandatory – most invocation errors are due to the model not knowing the constraints.
Parameters – with concrete examples (“RFC3339 format, e.g. 2024-03-15T14:30:00Z”), return value – with format.
1–5 real-world examples of invocation increase accuracy from ~72% to ~90%.

Practical principle: when an agent makes a mistake in tool selection – check the description first, not the model.