Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare destructiveHint=true, readOnlyHint=false, non-idempotent. The description adds that deletion is by sheet name, which is useful for identifying the target. However, it doesn't disclose irreversible data loss, required permissions, or what happens if the sheet doesn't exist. With annotations covering the safety profile, a 3 is appropriate – some added context but not rich behavioral detail.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.