Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds valuable behavioral context beyond annotations: it explains the deterministic ECitMatch primary-key behavior, the field requirements for a match, and how field completeness affects accuracy.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.