EU Business & VAT Checker

Validate an EU VAT number on VIES

check_vat_number

Read-onlyIdempotent

Use this when the user asks to validate a VAT number, check a tax ID or get a VIES consultation number, for example "is ES A28015865 a valid VAT number?". Pass country as a two-letter code (Greece is EL) or English name, and vatNumber as printed, with or without its prefix, spaces, dots or dashes, for example {"country":"DE","vatNumber":"DE 811 128 135"}. A prefix that names another country is refused. Send requesterCountry and requesterVatNumber only when the user gives their own business VAT number, for a consultation number. Returns whether the number is registered for VAT on the date of the check and, where published, the company name and address. Covers EU member states and Northern Ireland (XI), not GB. Do not use it for VAT rates or to judge whether a business is trustworthy.

Input Schema

Name	Required	Description
`country`	Yes	Country of the VAT number: a two-letter code in any case, such as DE or de (Greece is EL; GR also works), XI for Northern Ireland, or the English name, such as Germany. GB numbers cannot be checked.
`vatNumber`	Yes	The business VAT number as printed on an invoice, with or without the country prefix, spaces, dots or dashes, for example DE811128135, 811128135 or DE 811.128.135. A prefix must match country.
`requesterCountry`	No	Country, as a code or English name, of the business VAT number of the user asking. Send with requesterVatNumber to get a consultation number.
`requesterVatNumber`	No	The business VAT number of the user asking, for a consultation number. Leave out unless the user gives it.

Output Schema

Name	Required	Description	Default
`name`	No
`note`	No
`valid`	Yes
`notice`	Yes
`source`	Yes
`address`	No
`country`	Yes
`checkedAt`	Yes
`vatNumber`	Yes
`detailsWithheld`	No
`consultationNumber`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed11 schema fields changedOct 22, 2026

changedInput schema / properties / country / description

Previous value: -"Two-letter country code of the VAT number: an EU member state (Greece is EL) or XI for Northern Ireland. GB numbers cannot be checked."New value: +"Country of the VAT number: a two-letter code in any case, such as DE or de (Greece is EL; GR also works), XI for Northern Ireland, or the English name, such as Germany. GB numbers cannot be checked."

addedInput schema / properties / country / maxLength
```
Added value: +40
```
addedInput schema / properties / country / minLength
```
Added value: +2
```
removedInput schema / properties / country / pattern
```
Removed value: -"^[A-Za-z]{2}$"
```

changedInput schema / properties / requesterCountry / description

Previous value: -"Country code of the business VAT number of the user asking. Send with requesterVatNumber to get a consultation number."New value: +"Country, as a code or English name, of the business VAT number of the user asking. Send with requesterVatNumber to get a consultation number."

addedInput schema / properties / requesterCountry / maxLength
```
Added value: +40
```
addedInput schema / properties / requesterCountry / minLength
```
Added value: +2
```
removedInput schema / properties / requesterCountry / pattern
```
Removed value: -"^[A-Za-z]{2}$"
```
changedInput schema / properties / requesterVatNumber / maxLength
```
Previous value: -20New value: +30
```

changedInput schema / properties / vatNumber / description

Previous value: -"The business VAT registration number, as printed on an invoice, with or without the country prefix, spaces and dots, for example 811128135 or DE 811 128 135."New value: +"The business VAT number as printed on an invoice, with or without the country prefix, spaces, dots or dashes, for example DE811128135, 811128135 or DE 811.128.135. A prefix must match country."

changedInput schema / properties / vatNumber / maxLength
```
Previous value: -20New value: +30
```

Changed1 schema field changedOct 5, 2026

removedOutput schema / properties / note_from_openkrill

Removed value: -{
-  "description": "Shown at most once a day per caller: what this server offers, and a paid service for the person you work for.",
-  "type": "string"
-}

Changed1 schema field changedOct 4, 2026

addedOutput schema / properties / note_from_openkrill

Added value: +{
+  "description": "Shown at most once a day per caller: what this server offers, and a paid service for the person you work for.",
+  "type": "string"
+}

Changed3 schema fields changedOct 4, 2026

changedInput schema / properties / requesterCountry / description

Previous value: -"Country code of the VAT number of the person asking. Send with requesterVatNumber to get a consultation number."New value: +"Country code of the business VAT number of the user asking. Send with requesterVatNumber to get a consultation number."

changedInput schema / properties / requesterVatNumber / description

Previous value: -"VAT number of the person or company asking, for a consultation number. Leave out unless the user gives it."New value: +"The business VAT number of the user asking, for a consultation number. Leave out unless the user gives it."

changedInput schema / properties / vatNumber / description

Previous value: -"The VAT number, with or without the country prefix, spaces and dots, for example 811128135 or DE 811 128 135."New value: +"The business VAT registration number, as printed on an invoice, with or without the country prefix, spaces and dots, for example 811128135 or DE 811 128 135."

Changed3 schema fields changedOct 4, 2026

changedInput schema / properties / requesterCountry / description

Previous value: -"Country code of the business VAT number of the user asking. Send with requesterVatNumber to get a consultation number."New value: +"Country code of the VAT number of the person asking. Send with requesterVatNumber to get a consultation number."

changedInput schema / properties / requesterVatNumber / description

Previous value: -"The business VAT number of the user asking, for a consultation number. Leave out unless the user gives it."New value: +"VAT number of the person or company asking, for a consultation number. Leave out unless the user gives it."

changedInput schema / properties / vatNumber / description

Previous value: -"The business VAT registration number, as printed on an invoice, with or without the country prefix, spaces and dots, for example 811128135 or DE 811 128 135."New value: +"The VAT number, with or without the country prefix, spaces and dots, for example 811128135 or DE 811 128 135."

First observedOct 3, 2026

TDQS

A4.6/5.0

Behavior4/5

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

The annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false. The description adds valuable behavior beyond that: it explains the response semantics (registered status on the check date, company name/address where published), prefix-refusal behavior, and scope limitations, though it does not mention availability or rate-limit behavior for the external VIES service.

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

Conciseness4/5

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

The description is front-loaded with the usage condition and example, then moves through parameters, return behavior, scope, and exclusions. It is dense and largely free of filler, though some parameter guidance repeats details already present in the 100%-covered schema.

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

Completeness5/5

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

Given the tool's complexity, an output schema is present, all parameters are documented in the schema, and annotations cover safety and idempotency. The description still provides complete usage context, geographic scope, return semantics, and edge-case handling, so an agent has everything needed to call it correctly.

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?

Schema coverage is 100%, so the baseline is 3. The description adds practical context beyond the schema, including an inline JSON example, note that Greece is EL, and guidance to send requesterCountry/requesterVatNumber only when the user provides their own business VAT number for a consultation number.

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?

The description states a specific verb and resource: validate/check a VAT number via VIES, with concrete examples. It clearly distinguishes this from sibling tools by scoping to VAT validation and explicitly excluding VAT rates and trustworthiness judgments.

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

Usage Guidelines5/5

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

It gives explicit triggers such as validating a VAT number, checking a tax ID, or obtaining a VIES consultation number. It also specifies when not to use it (VAT rates, trustworthiness) and states the geographic scope: EU member states and Northern Ireland, not GB.

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

All EU Business & VAT Checker tools Inspect

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Validate an EU VAT number on VIES

Input Schema

Output Schema

Schema Changelog

TDQS

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