Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already provide readOnlyHint: true and openWorldHint: true, covering the key behavioral aspects (safe read, open schema). The description adds no additional behavior disclosure (e.g., caching, error handling). With annotations, the bar is lower, and the description does not contradict or add value.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.