Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden of disclosing behavioral traits. It only states 'get directory tree structure' without revealing specifics like recursion behavior, handling of hidden files, or that it is a read-only operation. The simplicity implies a safe read, but crucial behavioral details are omitted, so it earns a 2.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.