Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already establish the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lowered. The description adds genuine behavioral context by enumerating what the returned record contains — vote categories (for/against/absent/on leave), attendance, and 'recent' bills/votes — which matters since no output schema exists. It loses a point for the undefined 'recent' time window.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.