Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover the safety profile (readOnly, idempotent, non-destructive, non-open-world). The description adds domain behavior beyond annotations by noting that the explanation includes live tier thresholds and that matches are recorded immutably, which helps the agent understand what content the tool produces.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.