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

Annotations cover the safety profile (readOnly, idempotent, non-destructive, open world), and the description adds genuinely non-redundant behavior: exact cost, two accepted payment paths, a free daily quota requiring no key or payment, and the return shape ('one verdict and a cite_as line'). It also discloses coverage limits via the country list (financials only in GB, FR, NO, FI, NL).

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?

Information-dense and front-loaded: trigger, scope, contents, output, then cost. No filler sentences, but several clauses are stacked into run-on sentences, making the payment and free-tier details slightly harder to scan than necessary.

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 paid, multi-source aggregation tool with no output schema, the description covers everything an agent needs: what data is returned, what the output format looks like ('one verdict and a cite_as line'), what it costs, how to pay, and when it is overkill. No material gap remains.

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 baseline is 3; the description adds real guidance by saying the input is 'name or id, best with country', telling the agent to combine identifiers with a country for better resolution, which the schema does not state. It does not explain tradeoffs between the other identifiers (kvk, vat, domain), so it stops short of a 5.

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 (full due diligence on a European company) and enumerates exactly what the dossier contains: registers in 10 countries plus GLEIF, directors/owners/parents screened for sanctions and PEP, VAT, Peppol, website, financial health. It explicitly positions itself above an 'existence check', which distinguishes it from siblings like company_lookup and eu_company_check.

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?

Gives a clear trigger ('before a deal or large payment') and an explicit exclusion ('beyond an existence check'), plus the payment mechanics (0.15 USDC via x402, 75 credits, or 5 free calls/day) that gate invocation. It falls short of naming the cheaper sibling tools an agent should use for simple existence checks, leaving that mapping implicit.

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