Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already establish that the tool is read-only, idempotent, and non-destructive. The description adds meaningful behavioral context by revealing that results are filtered by an allowlist, which helps set expectations that not all organization projects may be returned. This is useful information beyond the structured annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.