Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is covered. The description adds the return content (metadata and document list), which matters because there is no output schema, but says nothing about pagination, truncation, or access restrictions on private libraries.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.