Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly/non-destructive/closed-world, and the description adds context beyond them: the cost model (budgetUsd default 2, max 10, held and released, hence free) and the auth requirement ('needs the write scope'). The write-scope note is slightly at odds with the read framing and could confuse, but the added cost/auth behavior is genuine value.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.