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einvoice-mcp

by makririch

E-Invoice MCPサーバー

DACH地域(ドイツ・オーストリア・スイス)の電子請求書用MCPサーバー — XRechnungの作成、検証、データ抽出を行います。Claude、Cursor、または任意のMCPクライアントから直接利用可能です。

npm version License: MIT

これは何ですか?

E-Invoice MCPは、ドイツのXRechnung標準に準拠した電子請求書の作成および検証を行うModel Context Protocolサーバーです。2027年以降、ドイツのすべての企業は電子請求書を送受信できる必要があります。このツールを使えば、その準備が整います。

Claudeに対して「Beispiel GmbH宛てにコンサルティング10時間分の請求書を作成して」と伝えるだけで、有効なXRechnung(UBL 2.1 XML)が生成されます。

Related MCP server: mcp-einvoicing-de

機能

  • XRechnung作成 — 構造化データから有効なUBL 2.1 XMLを生成(EN 16931 + XRechnung 3.0.2準拠)

  • 電子請求書検証 — 構文、必須項目、ドイツのビジネスルール(BR-DE)のチェック

  • データ抽出 — UBLまたはCII XMLから構造化データを読み取り

  • フォーマット情報 — 必須項目、税区分、単位コード、期限のリファレンス

  • 自動計算 — 正味金額、総額、税額を自動計算

  • プラグイン対応 — スタンドアロンでの実行、またはBuchPilot MCPサーバーへの統合が可能

  • 外部サービス不要 — すべてローカルで動作し、APIキーは不要

  • ネイティブ依存関係なし — Node.jsが動作するすべてのシステムで実行可能

法的期限

日付

内容

2025年1月1日

すべての企業は電子請求書を受信できる必要がある

2026年12月31日

PDF請求書は受取人の同意がある場合のみ許可

2027年1月1日

売上高80万ユーロ超の企業は電子請求書を送信する必要がある

2028年1月1日

すべての企業が電子請求書を送信する必要がある

不適切な電子請求書は、仕入税額控除の喪失(+6%の利息)につながる可能性があります。

インストール

前提条件

  • Node.js >= 18

npm (グローバル)

npm install -g einvoice-mcp

ソースから

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

設定

このMCPサーバーは設定不要です。APIキーや外部サービスは必要なく、すべてローカルで動作します。

利用方法

サーバーの起動 (スタンドアロン)

# Nach npm install -g:
einvoice-mcp

# Oder von Source:
npm start

# Entwicklung mit Auto-Reload:
npm run dev

サーバーはstdio経由で動作し、MCPメッセージを待機します。

Claude Desktopでの利用

詳細な手順については、Claude Desktopセットアップガイドを参照してください。

概要 — claude_desktop_config.json に以下を追加します:

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

例(Claudeでの自然言語による指示)

サーバーを設定した後、Claudeに以下のように尋ねることができます:

  • 「Beispiel GmbH宛てに、150ユーロのコンサルティング10時間分のXRechnungを作成して」

  • 「このXMLファイルは有効なXRechnungですか?」

  • 「このXMLから請求書データを抽出して」

  • 「XRechnungに必要な必須項目は何ですか?」

  • 「税区分にはどのようなものがあり、それぞれ何を意味しますか?」

  • 「私の会社はいつまでに電子請求書を送信できるようになる必要がありますか?」

クイックスタート

「5分で最初のXRechnungを作成する」ステップバイステップガイドは、docs/quickstart.mdにあります。

ツールリファレンス

パラメータ、入力例、出力例を含む全4ツールの完全なリファレンスは、docs/tool-reference.mdを参照してください。

概要

ツール

説明

create_xrechnung

構造化データからXRechnung (UBL 2.1 XML) を作成

validate_invoice

電子請求書XMLを検証 (構文 + BR-DEビジネスルール)

extract_data

UBLまたはCII XMLから構造化データを抽出

get_format_info

フォーマット、必須項目、コード、期限のリファレンス

BuchPilotとの統合

E-Invoice MCPは、BuchPilot MCPサーバーのプラグインとして統合できます:

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

組み合わせ例: BuchPilotでLexofficeの請求書を作成 -> データを抽出 -> XRechnungを生成 -> 電子請求書の完成。

対応標準

標準

バージョン

ステータス

XRechnung

3.0.2

作成 + 検証

EN 16931

—

XRechnungの基礎

UBL 2.1

—

XRechnungのXML構文

CII (Cross Industry Invoice)

—

抽出 (読み取り)

ZUGFeRD / Factur-X

2.3

抽出 (読み取り)、作成は計画中

FAQ / トラブルシューティング

「XMLを解析できませんでした」

  • XMLは整形式ですか?(すべてのタグが正しく閉じられていますか?)

  • 実際にUBLまたはCII請求書ですか?(ルート要素が <Invoice> または <CrossIndustryInvoice> である必要があります)

  • エンコーディングはUTF-8ですか?

検証で「BR-DE-13: Buyer Referenceは必須です」というエラーが出る

買い手参照(BT-10)はXRechnungで必須です。公共機関への請求書の場合、これはLeitweg-IDになります。B2B請求書の場合は、任意の参照番号(注文番号など)を指定できます。

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

検証で「BR-DE-21: 電話番号が推奨されます」という警告が出る

これは警告であり、エラーではありません。請求書は有効です。ただし、互換性を最大化するために、販売者の電話番号を指定することをお勧めします。

税区分にはどのようなものがありますか?

コード

名前

説明

税率

S

標準

通常の税率

19%, 7%

Z

ゼロ税率

0% (例: VAT免除の域内取引)

0%

E

免税

例: ドイツ付加価値税法第19条に基づく小規模事業者

0%

AE

リバースチャージ

受取人の納税義務 (ドイツ付加価値税法第13b条)

0%

K

域内取引

税免除の域内供給

0%

単位コードにはどのようなものがありますか?

コード

名前

説明

H87

個

個別の単位 (デフォルト)

HUR

時間

作業時間

DAY

日

労働日

MON

月

暦月

KGM

キログラム

重量

MTR

メートル

長さ

LTR

リットル

容量

MTK

平方メートル

面積

SET

セット/パッケージ

構成品

C62

単位 (汎用)

一般的な数量単位

サーバーは起動しているが、Claudeがツールを認識しない

  • claude_desktop_config.json が正しいか確認してください

  • 設定変更後はClaude Desktopを再起動してください

  • ログを確認してください: ~/Library/Logs/Claude/mcp.log (macOS)

ライセンス

MIT — 商用利用を含め、自由に使用可能です。

著者

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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