Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, destructiveHint=false, and openWorldHint=false, so safety is covered. The description adds a genuinely useful trait beyond the schema: the data is 'as last synced from Google', disclosing that results are a cached snapshot rather than a live query — material for an agent deciding whether to re-check. It omits any prerequisite that a GSC connection must exist, which caps it below 5.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.