Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations only declare openWorldHint and a title, so the description carries the burden and does so richly: auto-creation of unknown contacts, SYNCHRONOUS workflow and webhook firing on event:<name>, test-artifact tagging, exclusion from segment evaluation and campaign audiences, and reserved system prefixes. These are exactly the non-obvious traits an agent needs to avoid misdiagnosing results.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.