Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true. The description confirms the read operation and adds the specific source (X11 CLIPBOARD selection), but does not disclose additional behavior such as encoding, error handling, or the format of returned text beyond 'as text'.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.