Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and idempotentHint=true, so the read-only nature is covered. The description adds meaningful behavioral context beyond the annotations by listing the specific categories of metadata returned (valid filters, groupings, metrics, detail fields, citation fields), which is exactly what an agent needs to know before querying. No contradictions with annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.