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einvoice-mcp

by makririch

Servidor MCP de Factura Electrónica

Servidor MCP para facturas electrónicas en la región DACH: cree, valide y extraiga datos de XRechnung. Directamente desde Claude, Cursor o cualquier cliente MCP.

npm version License: MIT

¿Qué es esto?

E-Invoice MCP es un servidor del Model Context Protocol para la creación y validación de facturas electrónicas según el estándar alemán XRechnung. A partir de 2027, todas las empresas en Alemania deberán poder enviar facturas electrónicas; con esta herramienta estarás preparado.

Simplemente dile a Claude: "Crea una factura para Beispiel GmbH por 10 horas de consultoría" y obtendrás una XRechnung válida como XML UBL 2.1.

Related MCP server: mcp-einvoicing-de

Características

  • Crear XRechnung — XML UBL 2.1 válido a partir de datos estructurados (EN 16931 + XRechnung 3.0.2)

  • Validar factura electrónica — Comprobar sintaxis, campos obligatorios y reglas de negocio alemanas (BR-DE)

  • Extraer datos — Leer datos estructurados de XML UBL o CII

  • Información de formato — Referencia para campos obligatorios, categorías de impuestos, códigos de unidades y plazos

  • Cálculo automático — Los importes netos, brutos y de impuestos se calculan automáticamente

  • Compatible con plugins — Puede ejecutarse de forma independiente O integrarse en el servidor MCP de BuchPilot

  • Sin servicios externos — Todo se ejecuta localmente, no se necesitan claves API

  • Sin dependencias nativas — Se ejecuta en cualquier sistema con Node.js

Plazos legales

Fecha

Qué sucede

01.01.2025

Todas las empresas deben poder recibir facturas electrónicas

31.12.2026

Facturas PDF permitidas solo con el consentimiento del destinatario

01.01.2027

Empresas con >800.000 EUR de facturación deben enviar facturas electrónicas

01.01.2028

TODAS las empresas deben enviar facturas electrónicas

Las facturas electrónicas incorrectas pueden provocar la pérdida de la deducción del IVA soportado (+ 6% de intereses).

Instalación

Requisitos previos

  • Node.js >= 18

npm (global)

npm install -g einvoice-mcp

Desde el código fuente

git clone https://github.com/makririch/einvoice-mcp.git
cd einvoice-mcp
npm install
npm run build

Configuración

Este servidor MCP no requiere configuración. No se necesitan claves API ni servicios externos; todo se ejecuta localmente.

Uso

Iniciar el servidor (independiente)

# Nach npm install -g:
einvoice-mcp

# Oder von Source:
npm start

# Entwicklung mit Auto-Reload:
npm run dev

El servidor se ejecuta a través de stdio y espera mensajes MCP.

Uso en Claude Desktop

Consulta la Guía de configuración de Claude Desktop para obtener instrucciones detalladas.

Versión corta: añade esto a claude_desktop_config.json:

{
  "mcpServers": {
    "einvoice": {
      "command": "npx",
      "args": ["-y", "einvoice-mcp"]
    }
  }
}

Ejemplos (lenguaje natural en Claude)

Después de configurar el servidor, puedes preguntarle a Claude, por ejemplo:

  • "Crea una XRechnung para Beispiel GmbH por 10 horas de consultoría a 150 EUR"

  • "¿Es este archivo XML una XRechnung válida?"

  • "Extrae los datos de la factura de este XML"

  • "¿Qué campos obligatorios necesito para una XRechnung?"

  • "¿Qué categorías de impuestos existen y qué significan?"

  • "¿Hasta cuándo debe mi empresa poder enviar facturas electrónicas?"

Inicio rápido

Encontrarás una guía paso a paso "Crea tu primera XRechnung en 5 minutos" en docs/quickstart.md.

Referencia de herramientas

Encontrarás una referencia completa de las 4 herramientas con parámetros, entradas de ejemplo y salidas de ejemplo en docs/tool-reference.md.

Resumen rápido

Herramienta

Descripción

create_xrechnung

Crear XRechnung (UBL 2.1 XML) a partir de datos estructurados

validate_invoice

Validar XML de factura electrónica (sintaxis + reglas de negocio BR-DE)

extract_data

Extraer datos estructurados de XML UBL o CII

get_format_info

Referencia para formatos, campos obligatorios, códigos y plazos

Integración con BuchPilot

E-Invoice MCP puede integrarse como plugin en el servidor MCP de BuchPilot:

import { registerEInvoiceTools } from "einvoice-mcp";
registerEInvoiceTools(server);

Combinación: BuchPilot crea una factura en Lexoffice -> extraer datos -> generar XRechnung -> factura electrónica lista.

Estándares compatibles

Estándar

Versión

Estado

XRechnung

3.0.2

Crear + Validar

EN 16931

—

Base para XRechnung

UBL 2.1

—

Sintaxis XML para XRechnung

CII (Cross Industry Invoice)

—

Extraer (leer)

ZUGFeRD / Factur-X

2.3

Extraer (leer), creación planificada

FAQ / Solución de problemas

"No se pudo analizar el XML"

  • ¿El XML está bien formado? (¿Están todas las etiquetas cerradas correctamente?)

  • ¿Es realmente una factura UBL o CII? (El elemento raíz debe ser <Invoice> o <CrossIndustryInvoice>)

  • ¿La codificación es UTF-8?

La validación muestra el error "BR-DE-13: Buyer Reference es obligatorio"

La referencia del comprador (BT-10) es obligatoria en XRechnung. En facturas a organismos públicos, este es el Leitweg-ID. En facturas B2B, puede ser cualquier referencia (por ejemplo, número de pedido).

{
  "buyerReference": "04011000-12345-67"
}

La validación muestra la advertencia "BR-DE-21: Se recomienda el número de teléfono"

Esto es solo una advertencia, no un error. La factura sigue siendo válida. Para una mejor compatibilidad, deberías indicar un número de teléfono del vendedor.

¿Qué categorías de impuestos existen?

Código

Nombre

Descripción

Tipos impositivos

S

Estándar

Tipo impositivo normal

19%, 7%

Z

Tasa cero

0% (p. ej. intracomunitario con exención de IVA)

0%

E

Exento de impuestos

p. ej. pequeña empresa según el párrafo 19 UStG

0%

AE

Inversión del sujeto pasivo

Sujeto pasivo el destinatario (párrafo 13b UStG)

0%

K

Intracomunitario

Entrega intracomunitaria exenta de impuestos

0%

¿Qué códigos de unidades existen?

Código

Nombre

Descripción

H87

Pieza

Unidad individual (predeterminado)

HUR

Hora

Hora de trabajo

DAY

Día

Día laborable

MON

Mes

Mes natural

KGM

Kilogramo

Peso

MTR

Metro

Longitud

LTR

Litro

Volumen

MTK

Metro cuadrado

Superficie

SET

Set/Paquete

Conjunto

C62

Unidad (genérica)

Unidad de medida general

El servidor se inicia, pero Claude no reconoce las herramientas

  • Comprueba si el archivo claude_desktop_config.json es correcto

  • Reinicia Claude Desktop después de realizar cambios en la configuración

  • Comprueba los registros: ~/Library/Logs/Claude/mcp.log (macOS)

Licencia

MIT — Uso libre, también comercial.

Autor

MaKri — GitHub

Available Tools

6 tools
convert_formatA

Konvertiert E-Rechnungen zwischen UBL (XRechnung), CII (ZUGFeRD) und JSON. Converts e-invoices between formats: ubl_to_cii, cii_to_ubl, ubl_to_json, cii_to_json, json_to_ubl, json_to_cii.

ParametersJSON Schema
NameRequiredDescriptionDefault
directionYesKonvertierungsrichtung
inputYesInput-Daten: XML-String fuer ubl/cii, JSON-String fuer json
validate_outputNoOutput nach Konvertierung validieren (nur fuer XML-Output)

TDQS

A3.6/5.0
Behavior2/5

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

With no annotations provided, the description carries full burden but provides minimal behavioral information. It mentions what formats can be converted but doesn't disclose important traits like whether this is a read-only operation, potential side effects, error handling, performance characteristics, or authentication requirements. The description doesn't contradict annotations (none exist), but fails to provide adequate 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.

Conciseness5/5

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

The description is extremely concise with zero wasted words. It's front-loaded with the core purpose in the first sentence, followed by specific conversion directions. The bilingual presentation (German/English) is efficient for clarity. Every sentence earns its place.

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

Completeness2/5

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

Given the tool's complexity (format conversion with multiple directions), no annotations, and no output schema, the description is insufficient. It doesn't explain what the tool returns, error conditions, input format requirements beyond basic mentions, or how validation works. For a data transformation tool with 3 parameters, this leaves significant gaps in understanding.

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?

With 100% schema description coverage, the baseline is 3. The description adds some value by listing all six conversion directions, which helps understand the 'direction' parameter's enum values, but doesn't provide additional semantic context beyond what's already in the schema descriptions for 'input' and 'validate_output' parameters.

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 clearly states the tool's purpose with specific verbs ('konvertiert', 'converts') and resources ('E-Rechnungen', 'e-invoices'), and explicitly lists all six conversion directions. It distinguishes itself from sibling tools by focusing on format conversion rather than creation, extraction, validation, or information retrieval.

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?

The description provides clear context about when to use this tool (converting between UBL, CII, and JSON formats), but doesn't explicitly state when NOT to use it or mention alternatives. It doesn't compare with sibling tools like 'get_format_info' or 'validate_invoice' that might be relevant in some scenarios.

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

create_xrechnungC

Erstellt eine XRechnung (UBL 2.1 XML) aus strukturierten Daten. Konform zu EN 16931 + XRechnung 3.0.2. Creates a valid XRechnung XML from structured data.

ParametersJSON Schema
NameRequiredDescriptionDefault
invoiceNumberYesRechnungsnummer (eindeutig)
issueDateYesRechnungsdatum (YYYY-MM-DD)
dueDateNoFaelligkeitsdatum (YYYY-MM-DD)
paymentTermsNoZahlungsbedingungen (z.B. 'Zahlbar innerhalb von 30 Tagen')
sellerYesRechnungssteller
buyerYesRechnungsempfaenger
lineItemsYesRechnungspositionen
currencyNoWaehrung (ISO 4217)EUR
paymentMeansCodeNoZahlungsart: 30=Ueberweisung, 58=SEPA-Ueberweisung, 59=SEPA-Lastschrift58
ibanNoIBAN fuer Zahlung
bicNoBIC
bankNameNoName der Bank
buyerReferenceNoLeitweg-ID oder Kaeufer-Referenz (BT-10, Pflicht in XRechnung)
orderReferenceNoBestellnummer des Kaeufers (BT-13)
noteNoFreitext-Bemerkung

TDQS

C2.9/5.0
Behavior2/5

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

No annotations are provided, so the description carries the full burden. It states the tool creates a valid XRechnung XML, implying a write operation, but doesn't disclose behavioral traits such as error handling, validation steps, or output format details. This is inadequate for a complex tool with 15 parameters.

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 concise and front-loaded, stating the core purpose in one bilingual sentence. It avoids redundancy and wastes no words, though it could be slightly more structured by separating key points.

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

Completeness2/5

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

For a complex tool with 15 parameters, nested objects, and no annotations or output schema, the description is incomplete. It lacks details on behavioral aspects, error handling, and output expectations, leaving gaps that could hinder effective tool selection and invocation.

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%, so the schema already documents all parameters thoroughly. The description adds no additional parameter semantics beyond what the schema provides, such as explaining relationships between fields or usage examples. Baseline 3 is appropriate when schema does the heavy lifting.

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

Purpose4/5

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

The description clearly states the tool creates an XRechnung XML from structured data, specifying the format (UBL 2.1) and standards (EN 16931 + XRechnung 3.0.2). It distinguishes from siblings like 'create_zugferd' by focusing on XRechnung, though it doesn't explicitly compare them.

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

Usage Guidelines2/5

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

No explicit guidance on when to use this tool versus alternatives like 'create_zugferd' or 'convert_format'. The description mentions conformance to specific standards, which implies usage for XRechnung-compliant invoices, but lacks clear when/when-not scenarios or prerequisites.

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

create_zugferdB

Erstellt ZUGFeRD 2.3 CII XML (Factur-X). Returns CII XML for embedding into PDF/A-3. Creates ZUGFeRD-compatible e-invoice XML in CII format.

ParametersJSON Schema
NameRequiredDescriptionDefault
invoiceNumberYesRechnungsnummer (eindeutig)
issueDateYesRechnungsdatum (YYYY-MM-DD)
dueDateNoFaelligkeitsdatum (YYYY-MM-DD)
paymentTermsNoZahlungsbedingungen
sellerYesRechnungssteller
buyerYesRechnungsempfaenger
lineItemsYesRechnungspositionen
currencyNoWaehrung (ISO 4217)EUR
ibanNoIBAN fuer Zahlung
bicNoBIC
buyerReferenceNoLeitweg-ID / Kaeufer-Referenz (BT-10)
orderReferenceNoBestellnummer des Kaeufers (BT-13)
noteNoFreitext-Bemerkung

TDQS

B3.1/5.0
Behavior2/5

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

With no annotations provided, the description carries full burden for behavioral disclosure. While it states the tool creates XML for embedding into PDF/A-3, it doesn't mention whether this is a pure generation tool (no side effects), what permissions might be needed, error handling, or performance characteristics. The description is minimal and lacks important behavioral context for a creation tool.

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 efficiently structured in two sentences that convey the core functionality and output format. While it could be slightly more detailed about behavioral aspects, there's no wasted language or redundancy. The information is front-loaded with the primary purpose stated immediately.

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

Completeness2/5

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

For a complex invoice creation tool with 13 parameters, nested objects, and no output schema or annotations, the description is insufficient. It doesn't explain what the tool returns (beyond mentioning 'CII XML'), error conditions, validation performed, or how the generated XML should be used with PDF/A-3. The agent lacks crucial context for proper tool invocation.

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%, providing comprehensive parameter documentation. The description adds no parameter-specific information beyond what's in the schema. According to scoring rules, when schema coverage is high (>80%), the baseline is 3 even with no param info in the description, which applies here.

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 clearly states the tool's purpose with specific verbs ('Erstellt', 'Creates') and resources ('ZUGFeRD 2.3 CII XML', 'Factur-X', 'e-invoice XML'), and distinguishes it from siblings by specifying the exact format (ZUGFeRD 2.3 CII) and use case (embedding into PDF/A-3). It explicitly mentions the output format and application context.

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

Usage Guidelines2/5

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

The description provides no guidance on when to use this tool versus alternatives like 'create_xrechnung' or 'convert_format'. It doesn't mention prerequisites, constraints, or typical scenarios for choosing ZUGFeRD over other invoice formats, leaving the agent without contextual usage information.

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

extract_dataC

Extrahiert strukturierte Daten aus einer E-Rechnung (UBL-XML oder CII-XML). Extracts structured data from an e-invoice XML.

ParametersJSON Schema
NameRequiredDescriptionDefault
xmlNoE-Rechnung XML als String
base64NoBase64-kodierte XML-Datei

TDQS

C2.9/5.0
Behavior2/5

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states the tool extracts data but doesn't describe what happens if the XML is invalid, what structured data is returned (e.g., fields like invoice number, date), or any performance or error-handling traits. This is inadequate for a tool that processes XML input without output schema details.

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 brief and front-loaded, with the core purpose stated first in both German and English. The bilingual repetition is slightly redundant but doesn't significantly detract from efficiency. It avoids unnecessary elaboration, making it easy to parse.

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

Completeness2/5

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

Given the tool's complexity (processing XML for data extraction), lack of annotations, and no output schema, the description is incomplete. It doesn't explain what structured data is extracted, how errors are handled, or the format of the output, leaving critical gaps for the agent to understand the tool's behavior and results.

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?

The schema description coverage is 100%, so the schema already documents both parameters ('xml' as a string and 'base64' as a Base64-encoded XML file). The description adds no additional meaning beyond implying these are alternative input methods for e-invoice XML, which is already clear from the schema. This meets the baseline for high schema coverage.

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

Purpose4/5

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

The description clearly states the tool's purpose: 'Extracts structured data from an e-invoice XML.' It specifies the verb ('extracts'), resource ('structured data'), and source format ('e-invoice XML'), though it doesn't explicitly differentiate from sibling tools like 'validate_invoice' or 'convert_format'. The bilingual phrasing adds clarity but doesn't enhance differentiation.

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

Usage Guidelines2/5

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

The description provides no guidance on when to use this tool versus alternatives. It mentions the input formats (UBL-XML or CII-XML) but doesn't specify scenarios where extraction is needed over validation or conversion, nor does it mention prerequisites or exclusions. This leaves the agent with minimal context for tool selection.

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

get_format_infoB

Gibt Informationen ueber E-Rechnungs-Formate, Pflichtfelder, Steuer-Kategorien, Einheiten-Codes und gesetzliche Fristen zurueck. Useful reference for creating valid invoices.

ParametersJSON Schema
NameRequiredDescriptionDefault
formatNoWelches Format abfragenall
topicNooverview=Formatbeschreibung, required_fields=Pflichtfelder, tax_categories=USt-Kategorien, unit_codes=Einheiten, deadlines=Fristenoverview

TDQS

B3.2/5.0
Behavior2/5

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It states the tool returns information, implying it's a read-only operation, but doesn't mention potential side effects, error handling, rate limits, or authentication needs. This is a significant gap for a tool with no annotation coverage.

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 concise and front-loaded, with two sentences that efficiently convey the tool's purpose and utility. The first sentence lists the key information returned, and the second clarifies its use case. There's no unnecessary repetition or fluff.

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

Completeness3/5

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

Given the tool's moderate complexity (2 parameters with enums) and lack of annotations and output schema, the description is somewhat complete but has gaps. It covers the purpose and general use case but omits behavioral details like response format, error conditions, or how the returned information is structured, which is important for a reference tool.

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?

The schema description coverage is 100%, with clear enum descriptions for both parameters. The description adds minimal value beyond the schema by listing topics like 'required_fields' and 'tax_categories', but doesn't provide additional context on parameter interactions or usage examples. Baseline 3 is appropriate given the high schema coverage.

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

Purpose4/5

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

The description clearly states the tool's purpose: it returns information about e-invoicing formats, required fields, tax categories, unit codes, and legal deadlines. It specifies the resource (e-invoicing formats) and the type of information returned, though it doesn't explicitly differentiate from sibling tools like 'validate_invoice' or 'extract_data' beyond being a reference tool.

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?

The description implies usage as a reference for creating valid invoices, suggesting it should be used when needing format details. However, it lacks explicit guidance on when to use this tool versus alternatives like 'validate_invoice' or 'create_xrechnung', and doesn't specify prerequisites or exclusions.

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

validate_invoiceC

Prueft ob XML eine gueltige E-Rechnung (XRechnung/ZUGFeRD) ist. Validiert Syntax, Pflichtfelder und deutsche Business-Regeln (BR-DE). Validates e-invoice XML.

ParametersJSON Schema
NameRequiredDescriptionDefault
xmlNoE-Rechnung XML als String
base64NoBase64-kodierte XML-Datei
levelNoValidierungstiefe: syntax=well-formed, schema=Struktur, full=inkl. BR-DE-Regelnfull

TDQS

C2.9/5.0
Behavior2/5

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It mentions validation actions but lacks details on permissions, rate limits, error handling, or output format. For a validation tool with zero annotation coverage, this is insufficient, as it doesn't describe what happens during or after validation beyond the basic purpose.

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 concise and front-loaded, stating the core purpose in the first sentence and adding a brief English translation. Both sentences earn their place by clarifying the tool's function, though it could be slightly more structured to highlight key aspects like validation levels. No wasted words, but minor improvements in organization are possible.

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

Completeness3/5

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

Given the tool's moderate complexity (3 parameters, no output schema, no annotations), the description is minimally adequate. It covers the purpose but lacks context on usage, behavioral traits, and output expectations. With 100% schema coverage, it compensates partially, but for a validation tool without annotations or output schema, more completeness is needed to guide an AI agent effectively.

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%, so the schema already documents all parameters (xml, base64, level) with descriptions and enum values. The description adds no additional parameter semantics beyond what the schema provides, such as explaining trade-offs between 'xml' and 'base64' inputs or elaborating on 'level' choices. Baseline 3 is appropriate as the schema does the heavy lifting.

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

Purpose4/5

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

The description clearly states the tool's purpose: validating e-invoice XML against XRechnung/ZUGFeRD standards with syntax, mandatory fields, and German business rules. It uses specific verbs ('prüft', 'validates') and identifies the resource (XML). However, it doesn't explicitly differentiate from sibling tools like 'get_format_info' or 'extract_data', which might also involve XML inspection.

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

Usage Guidelines2/5

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

The description provides no guidance on when to use this tool versus alternatives. It doesn't mention sibling tools like 'create_xrechnung' or 'convert_format', nor does it specify prerequisites or contexts for validation. Usage is implied but not explicitly stated, leaving gaps for an AI agent to determine appropriateness.

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

Tool Schema Changelog

Recent tool additions, removals, and schema changes observed during successful MCP inspections.

  1. 6 tool updatesv0.1.2
    • First observedconvert_format
    • First observedcreate_xrechnung
    • First observedcreate_zugferd
    • First observedextract_data
    • First observedget_format_info
    • First observedvalidate_invoice

TDQS

A3.5/5.0

Scored across 6 tools

Disambiguation5/5

Each tool has a clearly distinct purpose with no overlap: convert_format handles format conversion, create_xrechnung and create_zugferd create specific invoice types, extract_data extracts data from invoices, get_format_info provides reference information, and validate_invoice validates invoices. The descriptions reinforce these distinct roles, making tool selection unambiguous.

Naming Consistency5/5

All tool names follow a consistent verb_noun pattern using snake_case: convert_format, create_xrechnung, create_zugferd, extract_data, get_format_info, and validate_invoice. This uniformity makes the tool set predictable and easy to navigate for an agent.

Tool Count5/5

With 6 tools, the server is well-scoped for e-invoice processing, covering creation, conversion, validation, data extraction, and reference information. Each tool earns its place without bloat, fitting typical expectations for a domain-specific server.

Completeness4/5

The tool set provides strong coverage for e-invoice workflows, including creation (XRechnung and ZUGFeRD), conversion between formats, validation, data extraction, and reference info. A minor gap is the lack of update or delete operations for invoices, but this is reasonable as invoices are typically immutable once created, and agents can work around this by recreating or modifying data externally.

Maintenance

ActivityInactive
ResponsivenessNo issues

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