Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, openWorldHint=true and destructiveHint=false, so the safety profile needs no restating. The description's one value-add is that results are denormalized with member accounts embedded, which tells the agent something about payload shape that the (empty) input schema cannot.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.