Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so the safety profile is covered without the description. The description adds only that the manifest 'includ[es] step results', a small structural hint, and says nothing about pagination, size, or failure modes for an unknown replay key.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.