Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety and side-effect profile is fully covered by structured data. The description adds only a modest amount of behavioral context (the router dispatches events to domain handlers), without saying what artifact is produced, where it is written, or whether it overwrites existing files.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.