Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is covered. The description adds valuable behavioral context: results are based on deterministic lexical relevance, and 'relevanceScore is not AI-confidence' is an important caveat preventing misinterpretation of search results.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.