Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds substantial behavioral context: it explains the output is AI-synthesized from multiple sources, lists the exact return fields, and describes the nature of the content (summary, takeaway, evidence, etc.). This goes well beyond annotations and gives the agent a precise mental model of the tool's behavior.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.