Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=false and destructiveHint=false, so the safety profile is covered. The description adds value by listing the fields returned, which matters since no output schema exists. It does not disclose ordering details, whether 'adet' caps at 20, or what happens with an unknown topic label.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.