SiteCheck Agent Intel & Dev

Checks up to 5 EU VAT numbers with the European

agent_intel_eu_vies_vat_batch_validator

Read-only

Checks up to 5 EU VAT numbers (country code + number, e.g. DE143208032) with the European Commission's VIES service and returns valid yes/no, the registered name and address when the member state releases them, and any member-state error. Some member states do not release names or addresses, and VIES can be unavailable for one country at a time. Related tools on this server, for a different need: agent_intel_dnssec_trust_chain_validator when you need DNSSEC status for a domain using Cloudflare's public. Price: $0.002 in USDC per successful call, paid with x402 (Base, Solana or Arc); failed calls are not charged.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "vat": "<vat>"
    },
    "name": "agent_intel_eu_vies_vat_batch_validator"
  }
}

Input Schema

Name	Required	Description	Default
`vat`	Yes	1 to 5 VAT numbers separated by commas, each with a 2-letter EU country code

Output Schema

Name	Required	Description	Default
`source`	No
`results`	No
`checkedAt`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedOct 23, 2026

TDQS

A4/5.0

Behavior4/5

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

Goes meaningfully beyond the readOnlyHint/openWorldHint annotations by disclosing that some member states withhold names and addresses (partial results are normal), that VIES can be unavailable per-country at a time (transient failure mode), and that billing is $0.002 per successful call via x402 with failures uncharged. That cost and degradation context is exactly what annotations cannot convey; only retry/partial-batch semantics are left unstated.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness3/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The core sentence is well front-loaded and dense with useful detail, and the pricing sentence earns its place. However, the sibling pointer is both off-topic for VAT validation and truncated mid-thought ("using Cloudflare's public."), which wastes attention and reads as boilerplate.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists, so return-value description is not required, and the description still covers the important caveats an agent needs (partial name/address availability, per-country outages, per-call pricing). What remains unaddressed is whether a malformed number in a batch invalidates the whole call and whether retrying after an outage is advised.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The input schema already documents the single `vat` parameter at 100% coverage (1-5 comma-separated numbers with 2-letter country codes), so the baseline is 3. The description reinforces the constraint and adds a concrete format example ("DE143208032"), which is a modest but real gain over the schema text.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ("Checks up to 5 EU VAT numbers ... with the European Commission's VIES service") and enumerates the outputs: valid yes/no, registered name/address, member-state errors. The batch cap and input format (country code + number) make it immediately distinguishable from any single-value validation tool in the sibling list.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is only implied: the batch framing ("up to 5") tells an agent this is the bulk path, and the note that failed calls aren't charged tells it failures are tolerated. There is no explicit when-to-use/when-not guidance, and the single "related tool" pointer is to DNSSEC validation, which is a different problem domain rather than an alternative for the same need.

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

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