Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The description adds rich behavioral context beyond the annotations: it reads from a cache, refreshes badge/action against mandate state, carries no shipping data, and exposes a specific error condition (offer_not_in_cache). This is fully consistent with the readOnly, idempotent, and non-destructive hints, and it tells the agent what to expect in terms of side-effects (none) and failure modes.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.