Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and openWorldHint=false, covering the safety profile, so the bar is lower. The description does add value beyond that by naming the warning categories (scam failures, invented data, inconsistency), which tells the agent what kind of risk signal it is retrieving, though it says nothing about return shape or volume.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.