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. The description adds one genuinely useful behavioral fact, the plan-support precondition, but says nothing about what the returned state contains, whether it can be empty, or any rate limits. With annotations doing the heavy lifting, this is an adequate-but-thin 3.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.