Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden; it discloses the returned content but says nothing about read-only safety, whether the values are static or recomputed, caching, or freshness guarantees. For a zero-parameter metadata lookup the risk is low, so the implicit read of static metadata is mostly self-evident, but the disclosure is thin.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.