Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so the agent knows it's a safe read operation. The description adds useful behavioral details about the conditional return values (authenticated:true when all connected, connect_url when missing credentials), which is beyond what annotations provide. Not contradicting annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.