list_supported_countriesList the EU company registers currently covered by lookup_eu_company / the paid eu-company endpoint, with each register's country, source, licence, whether officers are returned, and the identifier format. FREE. Call this to discover coverage before paying.
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations provided, but the description clearly states the tool is FREE and lists the fields returned, indicating a read-only listing operation. Lack of rate limit or pagination info is acceptable for a simple list with no parameters.
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 the main action. Every sentence adds value: first sentence defines output, second sentence gives usage guidance. No fluff.
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 adequately explains return fields and usage context. It is complete for a list tool without parameters, covering all necessary information.
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?
Input schema has zero parameters, so schema coverage is 100%. The description adds context about what is listed (countries, sources, licences, etc.) without needing to explain parameters.
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 lists EU company registers covered by the paid endpoint, specifying the details returned (country, source, licence, officers, identifier format). It distinguishes itself from siblings by referencing lookup_eu_company and validate_eu_vat.
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?
Explicitly says 'Call this to discover coverage before paying', providing clear guidance on when to use the tool (before paying for the paid endpoint). It implies not to use for actual lookups.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.
Each tool has a distinct purpose: listing supported countries, looking up a company (with a free jurisdiction detection and a paid full record), and validating EU VAT numbers. No overlap in functionality.
All tool names follow a consistent verb_noun pattern in snake_case: list_supported_countries, lookup_eu_company, validate_eu_vat. Easy to predict and read.
Three tools is appropriate for the domain of EU compliance covering VAT validation and company data lookup. Neither too few nor too many.
The set covers key operations: discovering coverage, detecting jurisdiction, and validating VAT. A minor gap is the lack of a tool to directly handle the paid service, but the descriptions guide the user externally.