Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the burden, and it does disclose a meaningful behavioral trait: the data comes from a public RSS feed, implying a read-only, free, no-auth operation. However, it does not disclose the number of stories returned, whether results are cached/stale, error behavior, or the structure of each story, which would matter for a tool with no output schema.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.