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

With no annotations provided, the description carries the full burden. It clearly states the tool returns an object with four fields, implying a read-only computation with no side effects. For a pure calculator, this is sufficient, though it could mention whether it modifies data or requires authorization.

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 description is concise with two short sentences. The first states the core purpose, and the second provides a pointer to related tools. No unnecessary words or redundancies.

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?

Given the tool has an output schema and is a simple calculator, the description is fairly complete. It specifies inputs, outputs, and references related tools. However, it lacks context on required privileges or error conditions, and could benefit from noting that Carrez is a French legal standard.

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% for the single 'rooms' parameter, so baseline is 3. The description only adds 'from a list of rooms', which minimally reinforces the schema's description. It does not clarify that 'length' and 'width' are in meters, which is already in the schema, nor explain the Carrez calculation specifics.

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 clearly states the tool calculates 'total floor area and Carrez habitable area' from a list of rooms, specifying the verb 'Calculate' and the resource 'floor area and Carrez habitable area'. It distinguishes itself from siblings like 'calculate_area' by mentioning Carrez, a specific French measurement, and referencing 'list_bundles' for related construction calculators.

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?

The description implies usage for floor area calculations involving Carrez habitable area, but does not explicitly state when to use this tool over alternatives such as 'calculate_area' or 'calculate_carpet_flooring'. It only points to 'list_bundles' for related calculators, offering weak guidance on selection.

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