# InkVoice — XRechnung & E-Invoicing (remote · api.inkvoice.net)

XRechnung and ZUGFeRD e-invoicing (EN 16931): create, validate, check Leitweg-IDs, German VAT.

- Trust score: 72/100 (medium)
- Change this week: +4
- Registry status: active
- Liveness: live
- Owner verified: no
- Last scored: 2026-09-20

## Components

- remote · `api.inkvoice.net`: 72/100 (this document), [markdown](https://verifymcp.io/servers/net-inkvoice-inkvoice/api.md), [page](https://verifymcp.io/servers/net-inkvoice-inkvoice/api)

## Channel facts

- Endpoint: `https://api.inkvoice.net/mcp`
- Transports: `streamable-http`
- Auth: `none`
- Version: `1.1.0`

## Trust breakdown

How this component scores in each security and reliability category. Every signal is checked automatically against the live server, and we only credit what we can confirm. Scores are 0–100 per category. Scoring method: https://verifymcp.io/docs/scoring (what has changed: https://verifymcp.io/docs/scoring/changelog)

Scored 2026-09-20.

- **Endpoint Security**: 63/100
  - The endpoint's TLS certificate is valid, in date, and uses a strong key.
  - Authorisation not fully verified: no authorisation is required to call this server, and 5 tool(s) never declared a destructiveHint. The MCP spec treats an absent hint as destructive by default, so we cannot call this surface safe.
  - HTTPS is enforced; there's no plaintext access path.
  - The HSTS (Strict-Transport-Security) header is present.
  - DNSSEC check failed: this domain isn't protected by DNSSEC.
- **Transport & Reachability**: 100/100
  - Verified streamable-http transport via a live MCP handshake.
- **Schema Quality & AI Usability**: 74/100
  - 100% of prompts and resources have a non-trivial description (not blank, and not just the item's name).
  - AI-judged instruction clarity (excellent).
  - Context-footprint check failed: tool/resource definitions use about 2306 tokens (~384/item across 6 items; 5 tools + 1 resources), over budget; trim descriptions and params.
  - Usage-examples check failed: none of the tools include examples.
- **Stability & Change Management**: 37/100
  - Stability observed for 11 of 30 days with no destabilising changes; credit accrues until the full window elapses.
- **Tool Coverage**: 100/100
  - 100% of tools have a non-trivial description (not blank, and not just the tool's name).
  - 100% of tool parameters carry a description.
- **Tool Safety**: 100/100
  - No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.
  - We read all 5 captured tool definition(s), and no name or description among them implies an irreversible operation.
  - An AI judge read all 7 captured unit(s) of tool text and found none that tries to manipulate the model reading it.
- **Capabilities**: 100/100
  - Implements a current MCP spec version (2026-07-28).

## Install

### How do I install the InkVoice — XRechnung & E-Invoicing MCP server?

InkVoice — XRechnung & E-Invoicing is a hosted endpoint at https://api.inkvoice.net/mcp, so there is nothing to install locally. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.

### Claude

```bash
claude mcp add --transport http net-inkvoice-inkvoice 'https://api.inkvoice.net/mcp'
```

### Cursor

```json
{
  "mcpServers": {
    "net-inkvoice-inkvoice": {
      "url": "https://api.inkvoice.net/mcp"
    }
  }
}
```

### VS Code

```json
{
  "servers": {
    "net-inkvoice-inkvoice": {
      "type": "http",
      "url": "https://api.inkvoice.net/mcp"
    }
  }
}
```

### Codex

```toml
[mcp_servers.net-inkvoice-inkvoice]
url = "https://api.inkvoice.net/mcp"
```

### opencode

```json
{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "net-inkvoice-inkvoice": {
      "type": "remote",
      "url": "https://api.inkvoice.net/mcp",
      "enabled": true
    }
  }
}
```

### OpenClaw

```bash
openclaw mcp add net-inkvoice-inkvoice --url 'https://api.inkvoice.net/mcp' --transport streamable-http
```

### Hermes

```yaml
mcp_servers:
  net-inkvoice-inkvoice:
    url: "https://api.inkvoice.net/mcp"
```

### Netclaw

```json
{
  "McpServers": {
    "net-inkvoice-inkvoice": {
      "Transport": "http",
      "Url": "https://api.inkvoice.net/mcp"
    }
  }
}
```

### Vellum

```bash
assistant mcp add net-inkvoice-inkvoice -t streamable-http -u 'https://api.inkvoice.net/mcp'
```

### Other

```json
{
  "mcpServers": {
    "net-inkvoice-inkvoice": {
      "type": "http",
      "url": "https://api.inkvoice.net/mcp"
    }
  }
}
```

The mcpServers block is a cross-client convention. Remote transports vary, so check your client's docs.

## Changelog

Every change recorded for this component, newest first. Days that predate change tracking, or that we cannot explain, say so: "we were watching and nothing happened" and "we were not watching" are different claims.

### 2026-09-20 (score 72, +1)

- [security regression] Judged manipulation: pass → unverified
- [security] The server rewrote its instructions, which are the text every model session reads
- [security] Tool “create_xrechnung” rewrote its description, which is the text the model reads
- [functional regression] Schema quality: 299 → 384
- [functional regression] Schema quality: 299 → 350
- [functional regression] Schema quality: good → unverified
- [functional] Schema quality: good → excellent
- [functional] Server version: 1.0.1 → 1.1.0
- [functional] New tool “create_zugferd”

### 2026-09-18 (score 71, +1)

No change was recorded against any check on this day. Stability & Change Management went from 27 to 30. That category is still filling its 30-day observation window: 8 days of observed history at the previous scan, 9 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-16 (score 70, +1)

- [functional] Server version: 1.0.0 → 1.0.1
- [cosmetic] Tool “calculate_vat” changed its title: Calculate German VAT
- [cosmetic] Tool “check_leitweg_id” changed its title: Check a Leitweg-ID
- [cosmetic] Tool “create_xrechnung” changed its title: Create an XRechnung
- [cosmetic] Tool “validate_einvoice” changed its title: Check an e-invoice

### 2026-09-14 (score 69, +1)

No change was recorded against any check on this day. Stability & Change Management went from 13 to 17. That category is still filling its 30-day observation window: 4 days of observed history at the previous scan, 5 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-12 (score 68, +1)

No change was recorded against any check on this day. Stability & Change Management went from 7 to 10. That category is still filling its 30-day observation window: 2 days of observed history at the previous scan, 3 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-10 (score 67, +1)

- [functional improvement] Stability: unverified → 0.03

### 2026-09-09 (score 66)

First indexed and scored.

## MCP tools (5)

### `create_zugferd` (~411 tokens)

Create a ZUGFeRD / Factur-X invoice

Builds a ZUGFeRD 2.x / Factur-X hybrid invoice from the same details create_xrechnung
takes, and returns it as a PDF file.

A hybrid is one invoice stated twice in one file: a PDF/A-3 document a person reads,
carrying the same invoice inside it as EN 16931 XML a machine books. This is the
format private-sector German B2B buyers generally want, where XRechnung is what public
bodies require. If the recipient is a public authority and gave you a Leitweg-ID, you
want create_xrechnung instead.

The embedded XML declares plain EN 16931 — the profile ZUGFeRD calls COMFORT — not the
XRechnung CIUS, because that CIUS is a statement about public-sector procurement.

Validation is identical to create_xrechnung: the same EN 16931 rules are applied before
anything is built, and a rejected call names the rules and business terms that failed.

What this does NOT do:
\- The result is a binary PDF returned as an attachment. It is not text and there is
  nothing useful to read in it — do not try to quote or summarise its contents. Offer
  it to the user as a file.
\- It does not validate against veraPDF or the Mustangproject validator. The document is
  built to be valid PDF/A-3 with the required Factur-X metadata, but that is our
  reading rather than a validator's verdict.
\- It handles ONE tax rate and one tax category for the whole invoice, exactly as
  create_xrechnung does.
\- It does not send the invoice anywhere, and there is no Peppol.
\- There is no logo and no custom styling. The PDF uses the default invoice layout.

Nothing is stored: no account, no invoice record, no retained personal data.

Input parameters:

- `invoice` (object, required): The invoice to turn into a ZUGFeRD / Factur-X document.

### `calculate_vat` (~269 tokens)

Calculate German VAT

Converts between net, tax and gross for a given VAT rate, in either direction.

Give an amount and say whether it is net or gross, and you get all three figures back
rounded to the cent. Germany's rates are 19 % (standard) and 7 % (reduced), but any
rate from 0 to 100 is accepted, so this also works for an Austrian or French invoice.

Rounding is half-away-from-zero, the convention invoices and tax authorities use, and
the three returned figures always reconcile: net plus tax equals gross exactly, with
no cent left over from rounding each separately.

What this does NOT do: it does not decide which rate applies to a supply, handle more
than one rate at a time, or know anything about reverse charge, intra-community supply
or the Kleinunternehmer rules. It is arithmetic, not tax advice.

Input parameters:

- `amount` (number, required): The amount to convert, in the invoice currency. Must not be negative.
- `basis` (string, required): Whether `amount` is the net figure (add tax to it) or the gross figure (take tax out of it).
- `rate` (number, required): VAT rate as a percentage, not a fraction: 19 means 19 %, not 1900 %.

### `create_xrechnung` (~414 tokens)

Create an XRechnung

Builds a German XRechnung 3.x electronic invoice (EN 16931, CII syntax) from invoice
details and returns the XML as text. This is the format German public-sector buyers
are legally required to receive, and that many private B2B buyers now ask for.

The EN 16931 business rules are checked before anything is built, and a rejected call
comes back naming the rules that failed and the business term (BT-xx) each concerns.
The ones worth getting right up front: tax category S requires a rate above 0 %,
categories Z, E and AE require exactly 0 %, E and AE additionally require a stated
exemption reason (BT-120), and both parties need an email address because XRechnung
makes the electronic address (BT-34, BT-49) mandatory. For a public-sector buyer, put
their Leitweg-ID in buyerReference (BT-10) — check_leitweg_id will verify it first.

What this does NOT do:
\- It does not validate against the KoSIT Prüftool. It applies our reading of EN 16931,
  which is not the same thing as the Schematron suite a receiving portal runs. Use
  validate_einvoice for a second look, and the official validator before a deadline.
\- It does not produce ZUGFeRD or Factur-X. There is no PDF and no embedded XML — this
  is a bare XML file. Use create_zugferd for the hybrid a private-sector B2B buyer
  usually wants.
\- It handles ONE tax rate and one tax category for the whole invoice. A document
  mixing 19 % and 7 % lines is not expressible here.
\- It does not send the invoice anywhere, and there is no Peppol.

Nothing is stored: no account, no invoice record, no retained personal data.

Input parameters:

- `invoice` (object, required): The invoice to turn into an XRechnung document.

### `check_leitweg_id` (~342 tokens)

Check a Leitweg-ID

Checks a German Leitweg-ID — the routing identifier that goes in BT-10 of an
XRechnung to a public authority. An invoice to a German public body with a wrong or
missing Leitweg-ID is rejected, so this is worth checking before building a document.

It verifies the structure (Grobadressierung of 2 to 12 digits, an optional
Feinadressierung of up to 30 alphanumerics, then two check digits) and recomputes the
ISO/IEC 7064 MOD 97-10 check digit, the same procedure an IBAN uses. When the check
digits are wrong it returns the ones the address parts actually imply, so the value
can be corrected rather than merely rejected. It also names the Bundesland the leading
two digits point at, or Bund for the federation.

One real limit: the check digit is computed over the address parts with the hyphens
removed, which is what KoSIT specifies, so it CANNOT detect a hyphen in the wrong
place. '04011000-1234512345-06' and '040110001-234512345-06' both pass. That is the
specification's behaviour, not a defect here.

What this does NOT do: it does not confirm that the ID belongs to a real authority or
that they are reachable. It checks the number, not the recipient — there is no
directory lookup.

Input parameters:

- `leitwegId` (string, required): The Leitweg-ID, e.g. '04011000-1234512345-06'. Surrounding whitespace is ignored.

### `validate_einvoice` (~363 tokens)

Check an e-invoice

Reads an existing electronic invoice and reports what is wrong with it. Accepts
XRechnung and ZUGFeRD XML in either EN 16931 syntax — CII (used by XRechnung and
ZUGFeRD) and UBL — and reports the syntax and profile it found along with the
invoice's key fields, so it also answers "what is this file?".

It checks the rules behind most real rejections: BT-10 buyer reference present, and
its Leitweg-ID check digit when it looks like one; BT-34 and BT-49 electronic
addresses present; tax category S not used at 0 %; BT-120 exemption reason present
for categories E and AE; line amounts summing to BT-106; net plus tax equalling the
BT-112 gross; BT-115 amount due matching gross less prepaid; and the due date not
falling before the issue date.

What this does NOT do:
\- It is NOT the KoSIT Prüftool and is not a substitute for it. It covers the rules
  that account for most rejections, not the full EN 16931 Schematron suite. A file
  that passes here can still be rejected by a Rechnungseingangsportal.
\- It does not check the XSD schema, so a structurally invalid document may parse here.
\- It reads XML only. A ZUGFeRD PDF must have its embedded XML extracted first — pass
  the XML, not the PDF.

Nothing is stored: the document is parsed in memory and discarded.

Input parameters:

- `xml` (string, required): The full XML text of the invoice. For ZUGFeRD, the XML extracted from the PDF, not the PDF itself.

## Diagnostics

Captured diagnostic sections: TLS, DNSSEC, Authorisation, Transports. The full working is on the page: https://verifymcp.io/servers/net-inkvoice-inkvoice/api#diagnostics

## Score history

- 2026-09-20: 72
- 2026-09-19: 71
- 2026-09-18: 71
- 2026-09-17: 70
- 2026-09-16: 70
- 2026-09-15: 69
- 2026-09-14: 69
- 2026-09-13: 68
- 2026-09-12: 68
- 2026-09-11: 67
- 2026-09-10: 67
- 2026-09-09: 66

## Common questions

### What is the InkVoice — XRechnung & E-Invoicing MCP server?

InkVoice — XRechnung & E-Invoicing is an MCP server listed in the public MCP registry as net.inkvoice/inkvoice. XRechnung and ZUGFeRD e-invoicing (EN 16931): create, validate, check Leitweg-IDs, German VAT. This page covers its hosted endpoint (https://api.inkvoice.net/mcp).

### Is the InkVoice — XRechnung & E-Invoicing MCP server safe to use?

InkVoice — XRechnung & E-Invoicing scores 72 out of 100 on VerifyMCP. That is a record of what we were able to check automatically, not an endorsement. The category breakdown on this page shows every signal behind the number, including the ones we could not confirm.

### What tools does the InkVoice — XRechnung & E-Invoicing MCP server expose?

InkVoice — XRechnung & E-Invoicing exposes 5 tools: create_zugferd, calculate_vat, create_xrechnung, check_leitweg_id, validate_einvoice. Their descriptions and schemas cost roughly 1,799 tokens of context every time the server is loaded.

### Does the InkVoice — XRechnung & E-Invoicing MCP server require authentication?

No. We connected to InkVoice — XRechnung & E-Invoicing without credentials and it answered, so anything it exposes is reachable by anyone who knows the address.

### Is the InkVoice — XRechnung & E-Invoicing MCP server still maintained?

InkVoice — XRechnung & E-Invoicing is still listed as active in the MCP registry. We last reached this channel on 20 September 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.

## Links

- Remote endpoint: https://api.inkvoice.net/mcp
- Website: https://inkvoice.net/mcp
- Changelog RSS feed: https://verifymcp.io/servers/net-inkvoice-inkvoice/api.xml
- Changelog JSON feed: https://verifymcp.io/servers/net-inkvoice-inkvoice/api.json
- HTML version of this page: https://verifymcp.io/servers/net-inkvoice-inkvoice/api