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

Annotations only cover read-only and open-world access, so the description carries extra weight and delivers: it discloses the server-side INSEE_API_TOKEN prerequisite, a 2-credit cost, and the important output-scoping fact that only the main establishment (siège) is returned, not all establishments. It omits error behavior for invalid SIRENs or rate limits, keeping it short of a 5.

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?

Front-loaded with the one-line purpose, then returned fields, requirement, example, caveat, and cost, each on its own line. The 'REQUIRED: siren (9-digit SIREN number)' line partially duplicates the schema, but the layout is scannable and nothing is padded.

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 compensates by naming the returned fields (legal name, NAF code, address, creation date, administrative status). Combined with the auth prerequisite, cost, and siège-only scoping, an agent has everything needed to call and interpret this tool.

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% and the schema already states '9 digits', so the baseline is 3. The description goes slightly beyond by restating the requirement and supplying a concrete example value with the expected response shape, which clarifies the expected format and output keys.

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 (get), resource (real estate business details), and the exact retrieval key (SIREN via INSEE API), plus enumerates the returned fields. It implicitly separates itself from search_real_estate_businesses by requiring an exact identifier, but never names or contrasts that sibling explicitly.

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?

Usage is implied: the description says details are fetched by SIREN, so an agent infers this is the follow-up to a lookup that already produced a SIREN. There is no explicit when-to-use statement, no when-not-to-use, and no pointer to search_real_estate_businesses for discovery, even though that sibling exists.

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