Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations declare readOnlyHint=true and destructiveHint=false, indicating a safe read operation. The description adds valuable behavioral context by listing the exact child notes returned (reviews, rebuttal, decision, metareview), which is not covered by annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.