Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and destructiveHint=false, indicating safe read-only behavior. The description adds context about the time window (last N days), default value of 7, and the curated nature of the news threads, which goes beyond annotations to set expectations on the scope and nature of results.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.