Billy MCP server

What the model can do

Billy (billy.dk) accounting for a Danish small business: invoices and credit notes with balances and overdue status, supplier bills, customers and suppliers, products and prices, the chart of accounts and tax rates. When you ask, can create and edit contacts and contact persons, create and edit draft invoices and credit notes, approve them into the books, email an invoice to a contact person or send it as an e-invoice, delete a draft, record or void a payment, create and approve bills, and create or edit products.

Reads

• billy_list_invoicesInvoices and credit notes in Billy, newest entry date first by default: number, customer, dates, state (draft, approved, voided), amount, VAT…
• billy_get_invoiceOne Billy invoice with its lines (product, description, quantity, unit price, amount) and the message printed on it.
• billy_list_billsSupplier bills in Billy, newest entry date first by default: supplier, dates, state, supplier's invoice number, amount, VAT, balance owed and paid…
• billy_list_contactsCustomers and suppliers in Billy: name, company or person, country, contact number, customer or supplier, payment terms.
• billy_list_productsProducts in Billy with their number, description, revenue account and unit price per currency.
• billy_list_accountsThe chart of accounts in Billy: number, name, group and whether it is a bank account that can take payments.
• billy_list_tax_ratesVAT and tax rates in Billy: name, abbreviation, rate, whether it applies to sales or purchases, active.

Acts, when you ask

These change something in Billy. The model is told to use them only when you ask for exactly that, and each one is granted by name: per team on a shared connection, by the owner on a personal one.

• billy_create_contactCreates a customer or supplier contact in Billy's books; nobody is emailed.
• billy_update_contactChanges a Billy contact's name, address, phone, registration number, EAN, payment terms or customer/supplier flags, or archives it…
• billy_add_contact_personAdds a contact person (name and/or email) to a Billy contact, so invoices can be emailed to them; nobody is emailed now.
• billy_create_invoiceCreates a DRAFT invoice in Billy for a customer, with product lines; or a draft credit note against an approved invoice (credit_note_for).
• billy_update_invoiceEdits a DRAFT Billy invoice's message, payment terms, tax mode or attention person (lines and date cannot change once created…
• billy_approve_invoiceApproves a draft Billy invoice: it is numbered and posted to the ledger and its state can never change again (a credit note is the only correction).
• billy_email_invoiceEmails a Billy invoice to one of the customer's contact persons (outside the company) with the subject and body given; it cannot be unsent.
• billy_send_e_invoiceSends an APPROVED Billy invoice as an e-invoice (OIOUBL over NemHandel/Peppol) to the receiver's 13-digit GLN…
• billy_delete_invoicePermanently deletes a DRAFT Billy invoice.
• billy_record_paymentRecords a payment in Billy against an approved invoice (money received into a bank account) or bill (money paid out)…
• billy_void_paymentVoids a Billy bank payment, so its invoice or bill is owed again; Billy says a voided payment can never be reinstated.
• billy_create_billCreates a DRAFT supplier bill in Billy with expense lines (account, tax rate, description, amount); nothing is booked or paid until it is approved.
• billy_approve_billApproves a draft Billy bill, posting it to the ledger as owed to the supplier; it cannot go back to draft.
• billy_create_productCreates a product in Billy with optional unit prices per currency and the revenue account its sales are coded to.
• billy_update_productChanges a Billy product's name, number, description or revenue account, or archives it (archived true) or restores it.

Connect it

First connect Billy on Dashboard → Connections, then add Memtro to your client once. The Billy tools appear alongside the tools of everything else you have connected; nothing is configured per connector.

claude plugin marketplace add memtro-org/claude-memtro
claude plugin install memtro@memtro --config api_key=sk-memtro-...

{
  "mcpServers": {
    "memtro": {
      "url": "https://platform.memtro.com/api/mcp",
      "headers": {
        "Authorization": "Bearer sk-memtro-..."
      }
    }
  }
}

{
  "mcp": {
    "memtro": {
      "type": "remote",
      "url": "https://platform.memtro.com/api/mcp",
      "headers": {
        "Authorization": "Bearer sk-memtro-..."
      }
    }
  }
}

Who may use it

The key identifies the person, and the server offers that person the tools they may use everywhere else in Memtro. A shared Billy connection is used by the teams an administrator granted it to, tool by tool, on the Permissions page; a personal connection is used by its owner alone, and its tools that act stay off until the owner allows them. See Teams and permissions and Connectors.

Ask it like this

• › Which invoices are overdue?
• › What do we owe suppliers this month?
• › What lines are on invoice 1042?
• › What is the unit price of the consulting day product?
• › Create a draft invoice for Northwind for two consulting days.

Questions

Is this an official Billy MCP server?

No. It is Memtro's MCP server with Memtro's Billy connector behind it: the connector reads Billy through its API with the credentials you connect on Dashboard → Connections, and Billy publishes nothing here. The same endpoint carries every other system you connect and Memtro's memory tools.

What does it cost?

Nothing on top of Memtro. One price per organisation by its number of users, from $50 a month for up to 10 users after a 7-day free trial, with every connector, the MCP server, jobs and memory included. You bring your own model keys.

Can it change anything in Billy?

Only when you ask, and only what it has been granted: create a contact (customer or supplier); edit or archive a contact; add a contact person to a contact; create a draft invoice or credit note; edit a draft invoice's message, terms or attention; approve a draft invoice into the books (permanent); email an invoice to a contact person (the customer receives it); send an approved invoice as an e-invoice by GLN (the receiver gets it); delete a draft invoice (permanent); record a payment against an invoice or bill; void a payment (permanent); create a draft bill; approve a draft bill into the books (permanent); create a product with prices; edit or archive a product. Every other tool reads, searches or lists. An administrator grants each acting tool by name per team, and a personal connection acts only after its owner allows it.

Which clients work?

Any MCP client that speaks Streamable HTTP: Claude Code, Cursor, Claude Desktop, OpenCode, Codex, Zed, Windsurf, Cline and the Anthropic and OpenAI SDKs. There is no local process to run; the server is remote and authenticated with your key.

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