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

With no annotations, the description carries the full burden of behavioral disclosure. It transparently lists all checks performed, the verdict format (pass/review/fail with per-check source, timestamp, coverage map), and discloses pricing and the no-charge-on-failure policy. It also explains the query example and country coverage. Minor gaps include no mention of authentication or error handling, but overall it provides substantial behavioral context.

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 front-loaded with the core purpose ('One-call verification of a European company') and efficiently packs essential details: checks performed, verdict output, query example, supported countries, disclaimers, and pricing. Every sentence contributes meaningful information without redundancy, making it concise despite covering multiple aspects.

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 no output schema, the description reasonably explains the return value as a pass/review/fail verdict with sources, timestamp, and coverage map. It also covers supported countries, expectations (factual, not credit score), and commercial terms. However, it omits details on error handling, authentication, and parameter format variations by country, which would be needed for fully autonomous invocation.

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 0%, so the description must add meaning. It clarifies the 'id' parameter as a national registry number, provides a concrete query example (country=FR, id=552032534), and lists supported country codes. It also implies the roles of 'vat', 'lei', 'eori', and 'domain' by naming them in the verification scope. This adds value beyond the bare parameter names, though it lacks detailed format specifications for each country.

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's purpose with a specific verb and resource: 'One-call verification of a European company.' It enumerates distinct checks (registry existence, insolvency signals, VAT, LEI, sanctions screening, EORI, domain age) and distinguishes it from siblings by offering a comprehensive single-call verification rather than a single-purpose check like validate_vat_eu or check_insolvency_fr.

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 context: use this tool when you need a comprehensive, one-call verification of a European company, as opposed to calling multiple sibling tools individually. It also clarifies what the tool is not ('Factual verification, not a credit score'), setting expectations. However, it does not explicitly name alternatives or provide 'when not to use' guidance, so it falls 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.