Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint, but the description adds valuable behavioral detail beyond that: it states 'no GitLab API call' (a specific limitation not in the annotations) and describes what the tool returns ('schemas, hints, destructive flags, and execute examples'). This gives the agent a concrete understanding of the tool's behavior and output without contradicting any annotation.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.