Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations provide comprehensive hints (readOnlyHint=true, destructiveHint=false, idempotentHint=true, openWorldHint=true), which already inform the agent that this is a safe, non-destructive, idempotent read operation. The description adds minimal behavioral context beyond annotations (none explicitly), but since annotations cover key traits well, the bar is lower. No contradiction with annotations exists.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.