Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden of behavioral disclosure. It does state a key guarantee ('never modifies source notes'), which is valuable. However, it does not disclose what it actually modifies (the index), potential side effects, concurrency behavior, error conditions, or whether permissions are required. The description provides one behavioral fact but omits many others that an agent would need for safe invocation.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.