Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly/idempotent/non-destructive and closed-world, so the safety profile is covered. The description adds genuinely non-obvious behavior beyond them: a missing document and an unpublished document return the identical not-found answer, which tells the agent not to infer publication state from the error.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.