Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations provide comprehensive behavioral hints (readOnlyHint: true, destructiveHint: false, idempotentHint: true, openWorldHint: true), which already inform the agent this is a safe, non-destructive, repeatable operation that may return partial data. The description adds minimal value beyond annotations - it confirms it's a GET operation but doesn't disclose additional behavioral traits like authentication requirements, rate limits, error conditions, or what 'security' data format to expect. 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.