Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations and no output schema, the description carries the full burden. It does disclose the content returned (source, date, licence, citation), which is useful given the absent output schema, but says nothing about format, permissions, or whether the metadata is static versus versioned.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.