Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so safety is fully covered. The description contributes only a field inventory, which is largely redundant with the existing output schema; it says nothing about shape, failure modes, or whether missing sections are omitted or null.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.