Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, openWorldHint=false and destructiveHint=false; the description reinforces this with concrete behavior ('does not execute, purchase, research live web content') and adds that unsupported requests are labeled explicitly, plus a cost/auth note ('Free, no signup'). It stops short of describing the shape of the returned routing result.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.