Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare this is a write (readOnlyHint=false), non-idempotent, and non-destructive. The description adds a real behavioral constraint beyond them: the test case must already belong to the test run, i.e. the failure mode for an unprepared target. It says nothing about permissions, whether a duplicate comment is appended each call, or the rich-text format caveats that drive the 'format' parameter.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.