Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the description's 'Read-only' is largely redundant. It does add genuinely non-structured context: an unknown platformId returns an error, and no API key is required. It doesn't disclose result ordering or pagination behavior, which the output schema may partially cover.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.