Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and openWorldHint=false, so safety and locality are covered structurally. The description adds genuine value by disclosing the return shape (excerpts plus source title and link), but says nothing about result count, ranking behavior, truncation, or how to handle zero results.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.