Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description should disclose behavioral traits. It only states 'List files stored in a project', omitting details such as read-only nature, error handling (e.g., invalid projectId), pagination, or whether file contents or only metadata are returned.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.