Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The annotations establish read-only, idempotent, non-destructive behavior, and the description adds valuable conditional details: the exact authenticated state, pending array behavior, and returned URLs when credentials are missing. This gives agents enough context to interpret results without over-describing.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.