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

Annotations already declare readOnly/idempotent/non-destructive, so the description adds genuinely new behavior: the download links lazily build their file when opened and no file is stored, and all needed formats must be requested in a single call. These are non-obvious operational traits an agent could not infer from annotations or schema.

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?

Purpose and outputs are front-loaded, then constraints, then sibling routing — a sensible order with almost no filler. It is dense and runs long, but nearly every clause carries a distinct constraint or exclusion.

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?

Covers territory limits, area-size limits, default radius, output summary content, available formats, and the lazy-download quirk. With an output schema present, the description need not detail return structure, and nothing an agent needs to invoke this correctly is missing.

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 coverage is 100%, so the baseline is 3; the description goes beyond it by stating the default radius (150 m) and the 0.6 km² cap, neither of which appears in the schema, plus guidance on how to pass 'place' and on batching formats in one call. It does not explain bbox ordering, but the schema already does that.

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?

Opens with a concrete verb+resource+scope: building heights around an address or small area in France, listing exactly what attributes are returned (metres, floors, use, year, altitude) and the source (IGN BD TOPO). This is clearly distinguishable from siblings like get_elevation or french_parcel.

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?

Explicit when-to-use (user asks how tall buildings are), explicit constraints (France only including Corsica and overseas departments, at most 0.6 km²), and explicit exclusions ('Never use the user's current location unless they type it'). It also routes away from two siblings by name: find_places is not needed first, and links must not be passed to open_gis_file.

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