Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden and does disclose a meaningful behavioral trait: this is a cached, local-only read that triggers no network or model activity. However, it does not state read-only semantics explicitly, data freshness, or what 'compact state' contains, leaving gaps for a status tool.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.