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

The readOnlyHint and openWorldHint annotations already cover the safety profile. The description adds meaningful behavioral detail: the 9999 IDCC code caveat, the x402 payment requirement, and the distinction that conventions_collectives_notes are technical codes, not lookups. This is exactly the kind of field-level nuance the structured schema would not 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?

The description is dense but efficient: it identifies the resource, lists the key data fields, flags an important interpretation caveat, and states the price in one tight paragraph. The caveat about 9999 is a minor digression but earns its place because it prevents a real misinterpretation.

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 an output schema, readOnlyHint, and a high-coverage input schema, the description is largely complete for invocation. It covers data source, contents, payment, and the key field caveat. It could be more complete by pointing to sibling tools for alternative data types, but that is not essential for correct use.

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 explains siren, api_key, and x_payment well. The description contributes little directly about parameters beyond noting the SIREN identifier and the payment cost, which the schema also captures. Baseline 3 is appropriate.

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 states a specific action and resource — 'Full official company profile of a French company by SIREN' — and enumerates the contents. It is clearly distinct from nearby siblings like get_french_company_file or get_french_company_financials, though it does not explicitly name an alternative to differentiate itself.

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 frames this as 'the core company data lookup for KYB and due diligence on France,' which gives clear context for when to reach for it. It does not explicitly state when not to use it or which sibling handles different use cases, so it stops short of a 5.

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