Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare destructiveHint=true and idempotentHint=false, so the safety profile is known. The description adds important operational context: passcodes are set via protect_url and never in chat, and member lists are managed through add_people. It does not explain the 'internal' mode, but overall adds value beyond structured fields.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.