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

Annotations already declare readOnlyHint, idempotentHint and non-destructive behavior, so the safety profile is fully covered elsewhere. The description adds the return field names, but with an output schema present this is largely redundant, and it never explains the underlying rule (e.g., rooms below the legal ceiling height are excluded), which is the one behavioral detail that would add value.

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?

Two sentences, front-loaded with purpose, then return fields and a navigation pointer. It is compact and wastes nothing, though the inline return-field list duplicates the output schema and slightly pads the entry.

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 deterministic calculator with full annotations and an output schema, the description covers purpose and return shape adequately; the only substantive gap is missing guidance on when to choose it over sibling area tools. Nothing required to invoke it correctly is absent.

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 a single 'rooms' parameter whose nested properties are all documented, so the schema carries the full burden. The description adds no meaning about the rooms array or what makes a room includable or excludable, leaving this at the baseline 3.

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 names a specific verb and resource, 'Calculate Carrez law surface area,' and pins down the domain with '(French legal measurement)', which separates it from generic siblings like calculate_area and calculate_floor_area. It is clear but stops short of an explicit sibling comparison, so it earns a solid 4 rather than 5.

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?

There is no statement of when to use this tool versus the many area calculators it sits beside; the only routing hint is 'See list_bundles for related immobilier calculators,' which points at discovery rather than selection criteria. An agent must infer the use case from the name alone.

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