Tool Design for Agents

Tools define the contract between deterministic systems and non-deterministic agents. Poor tool design creates failure modes that no amount of prompt engineering can fix.

The Consolidation Principle

If a human engineer cannot definitively say which tool should be used, an agent cannot do better.

Instead of: list_users, list_events, create_event Use: schedule_event (finds availability and schedules)

Tool Description Structure

Answer four questions:

1. What does the tool do?
2. When should it be used?
3. What inputs does it accept?
4. What does it return?