MCP — the Model Context Protocol — is how an AI assistant reaches a tool it does not have built in. InkVoice runs one at https://api.inkvoice.net/mcp, so an assistant can build a German e-invoice, read one it has been sent, or check a Leitweg-ID without you leaving the conversation to do it by hand.
Four of the tools need no account and no credential. That is deliberate: the questions they answer are the ones people ask before they have picked an invoicing product, and asking someone to sign up first is a strange way to answer "is this number formatted correctly".
- Builds an EN 16931 XRechnung (CII syntax) from invoice details you supply.
- Reads an e-invoice file and reports what it contains and where it looks incomplete.
- Checks a Leitweg-ID, including the ISO 7064 MOD 97-10 check digit.
- Calculates German VAT at 19 % or 7 %, net to gross or gross to net.
- With a token: lists your clients and invoices, reads one, exports its XRechnung, creates a client or a draft invoice.
- Send an invoice, email a client, or share a public link — no tool on this server has an outward-facing side effect.
- Delete or cancel anything.
- Replace the official KoSIT Prüftool, which is the tool a receiving portal runs. Use both.
- Give tax advice, or tell you whether your invoice satisfies an obligation.
The four tools that need no account
| Tool | What it does |
|---|---|
create_xrechnung | Produces an EN 16931 XRechnung file from seller, buyer, line items and a tax rate. One tax rate per invoice. |
validate_einvoice | Parses an e-invoice you paste in and reports its contents and likely problems. Not the Prüftool — see below. |
check_leitweg_id | Checks the structure and check digit of a Leitweg-ID, the routing identifier a German public buyer gives you. |
calculate_vat | German VAT both ways, at 19 % or 7 %, with the net, tax and gross figures separated. |
The server also exposes a reference resource, german_einvoicing_rules, which an assistant can read for background on the German e-invoicing rules rather than recalling them.
Connecting a client
Adding the server
- 1Use the URL as a remote MCP server
The address is
https://api.inkvoice.net/mcp. It speaks streamable HTTP, which is the current remote transport — there is nothing to install and nothing to run on your own machine. - 2Add it wherever your client takes a custom connector
Most clients have a field for a remote server URL. Paste the address above. The server is also listed in the official MCP Registry as
net.inkvoice/inkvoice, so a client that reads the registry can find it by name. - 3Stop there, unless you have an InkVoice account
With no credential you get the four tools above, which is the whole e-invoicing toolkit. Everything below is only useful if you already keep your invoices here.
- 4For your own data, add a token
In InkVoice, open Settings and create a personal access token. It begins
inkv_and is shown once. Send it as anAuthorizationheader —Bearer inkv_…— and six more tools appear.
The six tools a token unlocks
| Tool | What it does | Scope |
|---|---|---|
list_clients | Your clients, with an optional search term. | Read |
list_invoices | Your invoices, filterable by status, client and date. | Read |
get_invoice | One invoice in full, including line items and payments. | Read |
export_xrechnung | The XRechnung file for an invoice you already have. | Read |
create_client | Adds a client. | Read-write |
create_invoice_draft | Creates an invoice as a draft, whatever else is set. | Read-write |
Every tool resolves your workspace from the token itself rather than from anything the assistant passes in, so no prompt can widen what a token can reach. A read-only token cannot write, and no token can mint another token.
Nothing here sends anything
Emailing an invoice, sending a payment reminder, cancelling, deleting and creating a public share link are all absent from this server, and that is a decision rather than a backlog item. An assistant acting on a misread instruction should not be able to put a document in front of your customer, so the tools stop at the draft and leave the sending to you.
The same reasoning applies to the draft: create_invoice_draft creates a draft whatever the request says, so an invoice number is never consumed and nothing reaches a client until a person opens it.
Limits
- Without a token: 60 requests a minute, per address. Shared by everyone behind the same connection.
- With a token: 240 requests a minute, per token. The credential is the limit, not the address, so one busy assistant cannot spend a colleague’s budget.
- A refusal says how long to wait. Rejections carry a Retry-After header and a JSON body with the same number, so a client can pause rather than retry into the limit.
Questions
Not for the e-invoicing tools. Building an XRechnung, reading one, checking a Leitweg-ID and calculating VAT all work with no account and no credential. An account only matters for reaching your own clients and invoices.
No, and it is not meant to replace it. The Prüftool is what a receiving portal runs, and it is the authority on whether a document is accepted. validate_einvoice reads a file and tells you what is in it and what looks wrong, which is a faster loop while you are still fixing things. Run the Prüftool before your first real submission.
It is used to build or read the document in that one request and is not stored. The anonymous tools have no workspace to store anything in — they are the same engine behind the free tools on this site, which also keep nothing.
No. There is no tool on this server that emails, shares or sends anything, so the question does not arise regardless of what an assistant is asked to do.
Any client that supports remote MCP servers over streamable HTTP. It is listed in the official MCP Registry as net.inkvoice/inkvoice, so clients that read the registry can discover it without being given the URL.
Nothing for the four anonymous tools. The account tools read and write the workspace you already have, so they follow whatever plan you are on.
The same XRechnung generator, e-invoice viewer and VAT calculator run on this site with no account and no assistant.
Open the free tools