Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already mark the tool as read-only, idempotent, and non-destructive. The description adds meaningful behavioral detail by specifying exact return states: authenticated:true with empty pending[] when connected, and connect_url plus per-install URLs when credentials are missing. This explains output logic beyond the annotation basics.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.