Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered; the description adds that the content is public and free with no paywall, which is real behavioral context an agent cannot get from the annotations. It does not cover rate limits or failure behavior, but the output schema handles the return shape.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.