Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already establish readOnlyHint, idempotentHint, and non-destructive behavior, so the bar for additional disclosure is lower. The description adds useful behavioral detail beyond the schema: the special semantics of page='blog' and the expectation that slugs come from get_site_map. It does not contradict annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.