Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false and destructiveHint=false, so the safety profile is covered. The description adds the WGS84 requirement and the performance tradeoff of geometrie='centre' vs 'contour', but it says nothing about failure behavior when the point falls outside any parcel (sea, foreign territory) or how geometry size affects payload. Returned fields are listed even though an output schema exists, which is partly redundant.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The function statement is front-loaded and the sectioned layout (Fonction / Retourne / Cas d'usage / Exemples / Conseils) is scannable. However, the five use cases and three examples are near-duplicates that restate the same 'coordinates in, parcel out' idea three times, adding bulk without new information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a 5-parameter read-only tool with an output schema and full annotation coverage, the description supplies everything needed to invoke it correctly: input coordinate system, required lat/lon, and guidance on choosing the geometry type. The main gap is edge-case behavior when no parcel is returned for a given point.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100% with enums on both format and geometrie, so the baseline is 3. The description does add a nuance beyond the schema: 'centre' gives a fast minimal response while 'contour' returns exact boundaries, which conveys a cost/precision tradeoff. It says nothing about the 'champs' projection parameter or the format parameter, leaving the two least obvious params to the schema alone.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb and resource: reverse geocoding GPS coordinates into a cadastral parcel, plus the inverse of what a forward geocoder would do. It is clearly distinct from siblings like infoparcelle_parcelle_get or infoparcelle_geocoder_search, but it never names or contrasts those alternatives explicitly, so the agent must infer the boundary.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Five concrete use cases (map click, building GPS, mobile position) and a 'Conseils' block giving when-to-use advice for the geometrie options make the intended context very clear. What is missing is when-NOT to use it, i.e. pointers to infoparcelle_geocoder_search for address input or infoparcelle_parcelle_get when the parcel ID is already known.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.