RevClamp MCP Server

Validate EU/XI B2B VAT ID & VIES Reverse-Charge State

revclamp_validate_eu_vat_vies

Read-onlyIdempotent

Normalize EU-27 and Northern Ireland (XI) B2B VAT identifiers (including mandatory Greece ISO-3166 GR to EL prefix normalization) and evaluate cross-border 0% VAT reverse-charge eligibility, VIES consultation evidence, or MS_UNAVAILABLE circuit-breaker fulfillment hold actions. Read-only and non-destructive; supports deterministic simulation modes ('VALID', 'INVALID', 'MS_UNAVAILABLE') or real-time European Commission VIES SOAP/REST lookup ('LIVE'). Returns structuredContent containing ok, mode, statelessEphemeralAudit, simulatedViesLookup, tenantId, normalizedVat, reverseChargeEligible, and viesDecision (status, action, zeroRateAllowed, consultationId). Use this tool for EU/XI VAT tax compliance; use revclamp_reconcile_b2b_net_terms for wholesale Net-15/30/60 deposit and credit-note accounting.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "revclamp_validate_eu_vat_vies"
  }
}

Input Schema

Name	Required	Description	Default
`demo`	No	Optional simulation flag (boolean) for deterministic VIES gateway preset evaluation.
`viesMode`	No	VIES evaluation mode: 'FORMAT_ONLY' (deterministic EU/XI syntax validation without consultation; local engine default), 'VALID' (deterministic active VAT simulation; cloud endpoint default), 'INVALID' (deterministic rejected VAT simulation), 'MS_UNAVAILABLE' or 'GLOBAL_MAX_CONCURRENT_REQ' (deterministic member-state outage circuit-breaker simulation), or 'LIVE' (real-time European Commission VIES lookup).
`buyerVatId`	No	Required buyer EU or Northern Ireland VAT registration number to normalize and validate (e.g. 'DE123456789', 'GR123456789', 'NL123456789B01', 'XI123456789', max 40 chars).
`supplyType`	No	Cross-border transaction supply category: 'GOODS' (Directive 2006/112/EC Art. 138(1) intra-Community supply, default; permitted for Northern Ireland XI under Windsor Framework) or 'SERVICES' (Directive 2006/112/EC Art. 196 B2B reverse charge; excluded from EU VIES for Northern Ireland XI).	GOODS
`sellerCountry`	No	Two-letter EU-27 or XI member state prefix of the merchant's dispatch warehouse (e.g. 'DE', 'NL', 'FR', 'EL', 'XI'; 'GR' is automatically normalized to 'EL'; default: 'DE').
`consultationNumber`	No	Optional VIES requester consultation reference number (e.g. 'WAPIAAAAW998877', max 64 chars) to attach to deterministic 'VALID' mode tax audit records.

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedNov 9, 2026
- removedInput schema / required
```
Removed value: -[
-  "buyerVatId"
-]
```

Changed2 schema fields changedOct 31, 2026

addedInput schema / properties / supplyType

Added value: +{
+  "default": "GOODS",
+  "description": "Cross-border transaction supply category: 'GOODS' (Directive 2006/112/EC Art. 138(1) intra-Community supply, default; permitted for Northern Ireland XI under Windsor Framework) or 'SERVICES' (Directive 2006/112/EC Art. 196 B2B reverse charge; excluded from EU VIES for Northern Ireland XI).",
+  "enum": [
+    "GOODS",
+    "SERVICES"
+  ],
+  "type": "string"
+}

changedInput schema / properties / viesMode / description

Previous value: -"VIES evaluation mode: 'FORMAT_ONLY' (deterministic EU/XI syntax validation without consultation), 'VALID' (deterministic active VAT simulation, default), 'INVALID' (deterministic rejected VAT simulation), 'MS_UNAVAILABLE' or 'GLOBAL_MAX_CONCURRENT_REQ' (deterministic member-state outage circuit-breaker simulation), or 'LIVE' (real-time European Commission VIES lookup)."New value: +"VIES evaluation mode: 'FORMAT_ONLY' (deterministic EU/XI syntax validation without consultation; local engine default), 'VALID' (deterministic active VAT simulation; cloud endpoint default), 'INVALID' (deterministic rejected VAT simulation), 'MS_UNAVAILABLE' or 'GLOBAL_MAX_CONCURRENT_REQ' (deterministic member-state outage circuit-breaker simulation), or 'LIVE' (real-time European Commission VIES lookup)."

Changed3 schema fields changedOct 25, 2026

addedInput schema / properties / demo

Added value: +{
+  "description": "Optional simulation flag (boolean) for deterministic VIES gateway preset evaluation.",
+  "type": "boolean"
+}

changedInput schema / properties / viesMode / description

Previous value: -"VIES evaluation mode: 'VALID' (deterministic active VAT simulation, default), 'INVALID' (deterministic rejected VAT simulation), 'MS_UNAVAILABLE' (deterministic member-state outage circuit-breaker simulation), or 'LIVE' (real-time European Commission VIES lookup)."New value: +"VIES evaluation mode: 'FORMAT_ONLY' (deterministic EU/XI syntax validation without consultation), 'VALID' (deterministic active VAT simulation, default), 'INVALID' (deterministic rejected VAT simulation), 'MS_UNAVAILABLE' or 'GLOBAL_MAX_CONCURRENT_REQ' (deterministic member-state outage circuit-breaker simulation), or 'LIVE' (real-time European Commission VIES lookup)."

changedInput schema / properties / viesMode / enum

Previous value: -[
-  "VALID",
-  "INVALID",
-  "MS_UNAVAILABLE",
-  "LIVE"
-]New value: +[
+  "FORMAT_ONLY",
+  "VALID",
+  "INVALID",
+  "MS_UNAVAILABLE",
+  "GLOBAL_MAX_CONCURRENT_REQ",
+  "LIVE"
+]

First observedOct 25, 2026

TDQS

A4.1/5.0

Behavior4/5

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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, and the description redundantly confirms read-only/non-destructive. Beyond that it adds genuinely new behavior: the deterministic simulation modes, the LIVE real-time Commission lookup, circuit-breaker handling for MS_UNAVAILABLE, and the shape of the returned decision object. Rate limits and failure fallbacks are only implied, keeping it off a 5.

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?

Content is front-loaded: scope and verb appear before modes, return values and sibling routing. It is dense but earns most of its words; the only waste is restating read-only/non-destructive, which the annotations already declare.

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?

With no output schema, the enumerated return fields (viesDecision, zeroRateAllowed, consultationId, normalizedVat) usefully tell the agent what to expect, and each VIES mode's effect is explained. Given six optional parameters and a network-bound LIVE path, a brief note on latency or lookup failure handling would close the remaining gap.

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

Parameters3/5

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

Schema description coverage is 100% and the two enums are documented in detail, so the structured data already carries nearly all parameter meaning. The description reinforces the GR-to-EL normalization requirement, but that rule is also stated in the schema for sellerCountry, so added value is marginal and a baseline 3 is appropriate.

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 opens with a specific compound verb (normalize and validate) plus the exact resource (EU-27/XI B2B VAT identifiers) and the business outcome (reverse-charge eligibility / VIES state). It names a concrete normalization rule (Greek GR to EL) and explicitly separates itself from the accounting sibling, so an agent can distinguish it from revclamp_reconcile_b2b_net_terms without inspecting either schema.

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

Usage Guidelines4/5

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

It states the domain of use ('EU/XI VAT tax compliance') and routes wholesale Net-15/30/60 deposit and credit-note work to revclamp_reconcile_b2b_net_terms, which is an explicit alternative with a selecting condition. It does not spell out exclusions such as non-EU or B2C scenarios, so it falls just short of a full when/when-not map.

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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