Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations declare readOnlyHint=true and destructiveHint=false, but the description adds specific behavioral details: 'Aucun fetch, aucune citation observée' (no fetch, no observed citation). This goes beyond the generic read-only hint by clarifying the tool does not make network calls or rely on external data. It reinforces but also extends the annotation information.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.