Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already provide readOnlyHint and idempotentHint, so the safety profile is clear. The description adds behavioral details: it detects types, required fields, array shapes, nested objects, common formats (email, uri, date, date-time, uuid), and returns a schema compatible with json_schema_validate. No contradictions.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.