Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and destructiveHint=false, so the description isn't required to restate that. It adds value by mentioning the OData endpoint and $expand, but does not disclose behaviors like error handling, default fields, or pagination. With annotations covering safety, the description adds minor context, hence a 3.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.