Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false, providing safety profile. Description adds value by disclosing conditional behavior: returns authenticated:true/pending[] when all providers connected, or connect_url when credentials missing. This context beyond annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.