Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover read-only, idempotent, closed-world behavior, yet the description adds substantive traits: up to three distinct definitions with their source article and link, a fallback rule when the whole phrase has no entry (most specific word is looked up and named in the result), and a caveat that definitions are explanatory notes rather than statutory text.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.