Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It discloses the exact data set covered (all 19 jurisdictions, enumerated) and mentions that each includes codes and boundary sources, giving a clear picture of what the tool returns. It does not explicitly state that it is read-only, but its list semantics imply no side effects.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.