Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is known. The description adds behavioral context by explaining the conditional responses: when all providers are connected, it returns authenticated:true and empty pending[], and when credentials are missing, it returns connect_url. This goes beyond what annotations provide, adding valuable state-dependent behavior details.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.