Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and openWorldHint=true, so the description isn't required to restate these. It does add that the tool retrieves variables, which is a specific behavioral detail beyond the resource itself. However, it doesn't disclose what happens when no results are found, whether both identifiers can be provided, or any error conditions. With annotations covering the safety profile, the description adds modest value.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.