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

Annotations mark it readOnly/non-destructive, and the description goes well beyond them: it discloses that a full single-storey scene (walls, doors, windows, named rooms, roof) is returned, that it conforms to specific French dimension rules and passes cao_verifier with zero alerts, that only single-storey is supported 'for now', and that a second layout comes back as a variant. This is substantively more than the annotations convey.

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?

It is a dense single block, but it is front-loaded with the WHEN clause and the return contract before the caveats and workflow. A few clauses (dimension list, variant mention) could tighten, but nearly every sentence carries selection or invocation value.

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?

With no output schema, the description still spells out the return payload (complete scene plus rooms/areas plus the alternate layout as a variant), the two layout options, the single-storey limitation, and the downstream toolchain. Nothing an agent needs to invoke or route 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 description coverage is 100%, so the schema already documents all eight parameters, including enums, defaults and ranges. The description mostly restates schema content (bedroom sizing, kitchen open/closed, layout types) rather than adding format or interaction detail beyond it, so the baseline 3 applies.

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?

States a specific verb+resource (design/lay out a house from a brief) and explicitly contrasts it with checking or editing an existing scene, naming cao_verifier and cao_copilote. An agent can distinguish this generator from every sibling without opening a schema.

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?

Opens with an explicit WHEN condition ('asked to DESIGN a house from a brief... rather than to check or edit an existing scene') and closes with the follow-up routing: cao_copilote to retouch, cao_verifier after any edit, cao_generer_ifc or cao_permis. Both when and what-next are stated, not implied.

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