Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare read-only, idempotent, and non-destructive behavior, and the description adds substantial context beyond that: rate limiting with HTTP 429, the isError response for a nonexistent slug, no pagination, public-data-only content, new-to-old ordering, and the citation requirement for canonical_url. Nothing contradicts the annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.