Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It only states that it returns a JSON string, but does not disclose the nature of the info, whether it has side effects, or any performance implications. The read-only aspect is implied but not made explicit.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.