Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, non-destructive, open-world. The description adds the return contents (schema, themes, record count) and the prerequisite ordering, which is useful context beyond the annotations. No caveats about rate limits or missing datasets, keeping it short of a 5.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.