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), so the description's burden is lower. The description adds minimal value by specifying 'GET' which aligns with readOnlyHint, but doesn't provide additional context about what 'mounts.one' returns, error conditions, or any system-specific behaviors. No contradiction with annotations exists, but the description adds little beyond what annotations already declare.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.