invowerk

by invowerk.dev · remote · no sign-in to list tools · v1.0.1 · published by dev.invowerk

E-invoice checker for ZUGFeRD, Factur-X, XRechnung and Peppol BIS. Free web tool, API and MCP.

Changes · 3

Compare Registry entry

6 tools: 3 change things and 3 only read.

Scanned Oct 21, 2026

Deletes or cancels0Claude Code: deny
Can't be undone0Claude Code: ask
Changes things3Claude Code: ask: see these tools
Only reads3Claude Code: allow: see these tools

2 checks matched something in the tool definitions. No finding is not a safety guarantee. How the checks work.

claude mcp add --transport http xrechnung-e-invoice-validator https://api.invowerk.dev/mcp/

Findings

Matches of fixed checks, with the text they matched.

2 warn

Warngenerate_invoice
The server marks "generate_invoice" read-only (readOnlyHint: true), and its own name, description or input give the class "write".
Matched text
annotations: {"readOnlyHint":true,"openWorldHint":false}; The name "generate_invoice" says "generate": a word for a change.
What this check looks for
Warnconvert_invoice
The server marks "convert_invoice" read-only (readOnlyHint: true), and its own name, description or input give the class "write".
Matched text
annotations: {"readOnlyHint":true,"openWorldHint":true}; The name "convert_invoice" says "convert": a word for a change.
What this check looks for

Tools

Open a tool for its reasons and full description. Descriptions are the publisher's own words, shown as they are.

6 tools

Changes things 3Creates or changes something that can be changed back.Claude Code: ask

convert_invoiceConvert an e-invoice to UBL or CII.1 finding
Why it is in this group
- The name "convert_invoice" says "convert": a word for a change.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Findings
- Warn
  The server marks "convert_invoice" read-only (readOnlyHint: true), and its own name, description or input give the class "write".
  Matched text
  annotations: {"readOnlyHint":true,"openWorldHint":true}; The name "convert_invoice" says "convert": a word for a change.
  What this check looks for
Description, as the server wrote it
Convert an e-invoice to UBL or CII. The result is checked before it is returned. Input: `invoice_base64` is the base64 of an XML invoice or a ZUGFeRD / Factur-X PDF, at most 4 MB decoded; or pass the file as a download link in `file`. `target_syntax` is "ubl" or "cii". `target_flavor` is optional, "en16931" or "xrechnung"; without it the flavor of the source is kept. Returns `xml`, `syntax`, `flavor` and `self_validation` (`valid`, `finding_count`). invowerk checks the converted XML before answering and never returns an invalid document. Input that cannot be read or converted fails with an error message. Credits: 3 per call.
Annotations the server declares
- title: Convert an e-invoice between UBL and CII
- readOnlyHint: true
- openWorldHint: true
generate_invoiceCreate a valid EN 16931 e-invoice (UBL or CII XML) from JSON.1 finding
Why it is in this group
- The name "generate_invoice" says "generate": a word for a change.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Findings
- Warn
  The server marks "generate_invoice" read-only (readOnlyHint: true), and its own name, description or input give the class "write".
  Matched text
  annotations: {"readOnlyHint":true,"openWorldHint":false}; The name "generate_invoice" says "generate": a word for a change.
  What this check looks for
Description, as the server wrote it
Create a valid EN 16931 e-invoice (UBL or CII XML) from JSON. Input: `invoice` is a JSON object keyed on EN 16931 Business Terms, the same schema as `POST /v1/generate`, at most 4 MB. Main fields: `syntax` ("ubl" default, or "cii"), `flavor` ("en16931" default, or "xrechnung", which requires `buyer_reference`, the Leitweg-ID BT-10, and `payment_iban`), `invoice_number`, `issue_date` (YYYY-MM-DD), `currency`, `seller`, `buyer`, `lines`, `tax_breakdown`, `totals`. invowerk writes your amounts as given. It does not compute or correct them. Returns `xml`, `syntax`, `flavor` and `self_validation`. invowerk checks the XML before answering and never returns an invalid document. Invalid input, or XML that fails the check, returns an error, as does a busy (`engine_busy`) or overrunning (`engine_timeout`) generate. Credits: 5 per call.
Annotations the server declares
- title: Create an e-invoice from JSON
- readOnlyHint: true
- openWorldHint: false
render_invoiceRender an XML e-invoice (UBL or CII, e.g.No findings
Why it is in this group
- Nothing in its name or description says what it does, so it is counted as a write.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Description, as the server wrote it
Render an XML e-invoice (UBL or CII, e.g. XRechnung) as a readable HTML page. invowerk uses the KoSIT XRechnung visualization. Use it to show a person what an e-invoice contains. Input: `invoice_base64` is the base64 of the XML, at most 4 MB decoded, or pass the file as a download link in `file`. PDFs are not accepted. `lang` sets the label language, "de" (default) or "en". Returns `html` (a complete HTML document), `lang`, `flavor` (e.g. "xrechnung") and `syntax` (e.g. "ubl_invoice"). A file that is not an XML invoice, malformed XML or XML with a DOCTYPE fails with an error message, and so does a busy (`engine_busy`) or overrunning (`engine_timeout`) render. Credits: 1 per call.
Annotations the server declares
- title: Render an e-invoice as HTML
- readOnlyHint: true
- openWorldHint: true

Only reads 3Looks things up and changes nothing.Claude Code: allow

explain_errorsExplain rule codes in plain language.No findings
Why it is in this group
- The name "explain_errors" says "explain": a word for reading.
Description, as the server wrote it
Explain rule codes in plain language. Works without an API key. Covers the codes of `validate_invoice` findings and hints: EN 16931, XRechnung, ZUGFeRD and invowerk's own hint codes (IW-*). Input: `codes` is a list of one or more codes, e.g. ["BR-CO-18", "BR-DE-21"]. Duplicates are removed. `lang` is "de" (default) or "en". Returns `lang` and `explanations`. Each explanation has `title`, `meaning`, `causes`, `fixes`, `severity`, `standard`, `bt_refs`, `xpath_hints` and `explain_url` (the German page for the code). If any code is unknown, the call fails and names the unknown codes. Credits: free. This tool is not metered.
Annotations the server declares
- title: Explain error codes
- readOnlyHint: true
- openWorldHint: false
parse_invoiceRead an existing e-invoice into JSON keyed on EN 16931 Business Terms.No findings
Why it is in this group
- The description's first verb is "read": a word for reading.
Description, as the server wrote it
Read an existing e-invoice into JSON keyed on EN 16931 Business Terms. The JSON is the input format of `generate_invoice`, so you can edit it and create the invoice again. Input: `invoice_base64` is the base64 of an XML invoice (UBL or CII) or a ZUGFeRD / Factur-X PDF, at most 4 MB decoded; or pass the file as a download link in `file`. A PDF may have at most 500 pages and 16 attachments. Returns `model` (the invoice as JSON), `detection` (`syntax`, `flavor`, `customization_id`) and `source` ("xml" or "pdf-embedded"). A file that cannot be read fails with an error that starts with an error code, e.g. a PDF without embedded XML, a UBL credit note, malformed XML, or a busy (`engine_busy`) or overrunning (`engine_timeout`) read. Credits: 2 per call.
Annotations the server declares
- title: Read an e-invoice into JSON
- readOnlyHint: true
- openWorldHint: true
validate_invoiceCheck an e-invoice against EN 16931 and German rules.No findings
Why it is in this group
- The name "validate_invoice" says "validate": a word for reading.
Description, as the server wrote it
Check an e-invoice against EN 16931 and German rules. Input: `invoice_base64` is the base64 of an XML invoice (UBL or CII) or a ZUGFeRD / Factur-X PDF, at most 4 MB decoded; or pass the file as a download link in `file`. `explain=true` adds an explanation to findings whose rule has one, in `lang` ("de" or "en"). `valid` is the result. For XRechnung the KoSIT validator decides. If it is unreachable, invowerk's own check with the same rules decides, `verdict_source` is "local" and `official_degraded` is true. `disagreement` is true when both ran and differ. `findings` lists each problem with `rule_id`, `severity` and `message`; pass the codes to `explain_errors` (free). `pdfa_verdict` is the PDF/A check of a PDF. `hints` never change `valid`. Unreadable input returns a finding, not an error. It fails with an error when the check is busy (`engine_busy`), ran longer than 20 s (`engine_timeout`) or the XML has more than 100,000 elements (`document_too_complex`). Credits: 1 per call.
Annotations the server declares
- title: Check an e-invoice
- readOnlyHint: true
- openWorldHint: true

This is not a safety rating, and no finding is not a safety guarantee. The groups and findings come from fixed checks of the tool definitions the server returned on the date shown, not from its code or what it does when called. How the checks work.

Install

Pinned to version 1.0.1. Values in angle brackets are yours to fill in.

claude mcp add --transport http xrechnung-e-invoice-validator https://api.invowerk.dev/mcp/

Run in a terminal.

Claude Code permissions

Allow the reads, ask before a change, deny the deletes. Paste into .claude/settings.json.

.claude/settings.json

{
  "permissions": {
    "allow": [
      "mcp__xrechnung-e-invoice-validator__validate_invoice",
      "mcp__xrechnung-e-invoice-validator__explain_errors",
      "mcp__xrechnung-e-invoice-validator__parse_invoice"
    ],
    "ask": [
      "mcp__xrechnung-e-invoice-validator__render_invoice",
      "mcp__xrechnung-e-invoice-validator__generate_invoice",
      "mcp__xrechnung-e-invoice-validator__convert_invoice"
    ],
    "deny": []
  }
}

Tools that only read are allowed, tools that change things ask first, tools that delete or cancel are denied. It assumes the server is installed as xrechnung-e-invoice-validator. Review it before you use it.

Keep track

Get told when this server's tools change: a new tool, a new description, a new class.

https://anlyon.dev/servers/dev.invowerk/xrechnung-e-invoice-validator/changes.xml

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Source: MCP Registry · repository. Synced Oct 21, 2026, 18:11 UTC.

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