Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and non-destructive, so the safety profile is supplied structurally. The description adds real behavioral value by disclosing that it fetches the sitemap and issues GET requests to validate a sample of URLs, which hints at side effects and runtime cost, but it says nothing about how many requests, rate limits, or failure handling.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.