Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare the tool read-only and non-destructive, so the description only needs to add behavior beyond that. It does so by disclosing the fallback behavior: when query is used, the tool loads the first matching live listing, and it notes the detail level returned. It does not cover every edge case, but the annotation coverage lowers the burden.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.