Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Description adds behavioral context beyond annotations: mentions the large dataset (100K+), return fields (ID, name, coordinates, elevation, coverage dates), and historical depth (some from 1700s). Annotations already indicate read-only, idempotent, non-destructive behavior.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.