Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Beyond the readOnlyHint/openWorldHint annotations, the description discloses genuinely useful behavior: an upstream cap of ~5 stores, proximity-based ranking, and that results are not pickup-only. These are non-obvious constraints an agent could not derive from the schema or annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.