Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The description adds value beyond annotations by revealing that it demotes other contacts. Given annotations already indicate non-read-only and idempotent behavior, this disclosure of side effects is sufficient. It could mention access requirements or confirmation, but it's adequate.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.