Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already provide readOnlyHint, idempotentHint, and openWorldHint, so the description borrows on those. It adds significant transparency: cost ($0.08/call), grounding in an independent live search index (not training data), the precise return format ({query, answer, citations, citationCount}), and payment instructions. This goes well beyond annotations, covering both safety and operational details.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.