Creating an invoice, posting a voucher and sending an invoice to a customer are all one call away, which is the point and also the risk: these are accounting records, not drafts. Reads and writes are clearly separated by tool name, so a setup that only needs answers can be reasoned about before you hand an agent the same token that can post entries.
A server over the Fortnox REST API v3, covering the parts of a small business's ledger an assistant can usefully touch: invoicing, customer and supplier records, journal entries, orders and quotes, and the reference data behind them.
- Invoices listed, read, created, sent, and their payments checked — `list_invoices`, `get_invoice`, `create_invoice`, `send_invoice`, `get_invoice_payments`
- Customers listed, read and created — `list_customers`, `get_customer`, `create_customer`
- Supplier invoices listed and created, and a supplier read, for tracking bills and expenses — `list_supplier_invoices`, `get_supplier`, `create_supplier_invoice`
- Journal entries listed and created, plus the chart of accounts and the financial year — `list_vouchers`, `create_voucher`, `get_accounts`, `get_financial_year`
- Company information, projects and cost centres — `get_company_info`, `list_projects`, `list_cost_centers`
- Sales orders listed and quotes created — `list_orders`, `create_offer`
A Fortnox OAuth2 access token in `FORTNOX_ACCESS_TOKEN` — sign up as a developer at developer.fortnox.se and create an integration to get the credentials. Node.js, since it is launched with `npx -y fortnox-mcp-server`; the package is `fortnox-mcp-server` (1.0.0), or install from a clone and point at `dist/index.js`. The Fortnox API rate limit is 25 requests per 5 seconds.
One command plus a key — npx -y fortnox-mcp-server, then supply credentials