Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, and non-destructive behavior, so the description does not need to repeat those. It adds meaningful conditional behavior: fully connected returns authenticated:true with empty pending[], while missing credentials produce connect_url and per-install URLs.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.