Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, openWorldHint=false, and idempotentHint=true. The description adds that the tool returns a routing list of sibling sites and their MCP endpoints, which is consistent with those annotations and provides useful behavioral context beyond the structured metadata.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.