Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds only the REST path (GET /v1/ad-accounts/{id}), which restates the read nature rather than adding context such as auth requirements, error behavior for unknown ids, or whether the response includes synced metrics.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.