Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, non-destructive, and openWorldHint, so the safety profile is covered. The description adds the nature of RDAP as a WHOIS replacement and the shape of results, but says nothing about caching behavior, rate limits, or failure modes for unregistered domains. Adds moderate value on top of annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.