Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover read-only, open-world, idempotent, and non-destructive behavior, so the description does not need to restate those. The description adds useful behavioral context: pagination, downloadable deliverable files (PDF, CSV, JSON), and the conditionally available findings screenshot archive.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.