Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It transparently discloses the output contents (columns, numeric flags, row count, provenance banner) and its role as the schema-introduction tool. It doesn't explicitly state read-only behavior, but the nature of the output makes that obvious. It adds useful context about being a first-step call.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.