Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=false and destructiveHint=true, so the safety profile is covered by structured data. The description adds the meaningful scoping fact that this affects every user without exception, but it says nothing about irreversibility, permissions required, or throttling for what is effectively an irreversible mass operation.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.