Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already mark the tool readOnly, openWorld, idempotent, and non-destructive. The description further adds operational context: no API key needed, callable immediately, and the relationship between the catalog and tools/list vs tools/call. This adds material behavioral context beyond 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.