MCP server for Quaderno — tax-rate calculation, invoices, contacts, products, receipts & expenses. Hosted by usefulapi — connect from Claude, Cursor, or any MCP client.
Team and Enterprise: an Owner adds the connector for the organization first.
Run this command, then run /mcp in Claude Code to log in:
Add to Cursor or add this to ~/.cursor/mcp.json:
{
"mcpServers": {
"quaderno": {
"url": "https://quaderno.usefulapi.io/mcp"
}
}
}Add to VS Code or add this to .vscode/mcp.json:
{
"servers": {
"quaderno": {
"type": "http",
"url": "https://quaderno.usefulapi.io/mcp"
}
}
}Other MCP clients (Windsurf, Cline, Zed and more): add the URL as a remote MCP server (Streamable HTTP). The client then opens the login page in your browser. Do not add an Authorization header: see Before you connect.
The login page asks for your Quaderno API key and Account subdomain.
Find your API key in Quaderno → your account → API keys. Your key is used only to call the API on your behalf and to derive a private account id; it is never shown to anyone.
Add only the URL. Do not add an Authorization header or an API key to the client config. The server signs you in with OAuth: the login page asks for your Quaderno API key and Account subdomain. If the config has such a header, remove it: some clients then send that header instead of the login token, and every call fails with 401.
Turn on the Quaderno connector, then ask in plain words. The AI picks the tools.
| Tool | Type | What it does |
|---|---|---|
ping | read | Ping (verify auth) Verify the API key and connection by pinging Quaderno. Returns account/authentication status. Quaderno API: GET /ping. |
calculate_tax | read | Calculate tax rate Calculate the correct tax rate/amount for a sale given the customer's location and product. This is Quaderno's flagship endpoint — it applies the right VAT / GST / US sales-tax rules per jurisdiction. READ-ONLY (no record is created). Quaderno API: GET /tax_rates/calculate. Returns { name, rate, country, region, county, city, tax_code, status (taxable|non_taxable|not_registered|reverse_charge), tax_amount, subtotal, total_amount }. |
list_invoices | read | List invoices List invoices, newest first, with optional filters. Quaderno API: GET /invoices. Returns invoice objects (id, number, issue_date, due_date, currency, contact, items, taxes, payments, state, total_cents, subtotal_cents), wrapped as { data, pagination } when more pages exist. |
get_invoice | read | Get an invoice Fetch a single invoice by id (full object incl. items, taxes, payments, permalink, pdf). Quaderno API: GET /invoices/{id}. |
list_contacts | read | List contacts List contacts (customers/vendors), newest first. Quaderno API: GET /contacts. Returns contact objects (id, kind, first_name, last_name, contact_name, email, country, tax_id, tax_status, …), wrapped as { data, pagination } when more pages exist. |
get_contact | read | Get a contact Fetch a single contact by id. Quaderno API: GET /contacts/{id}. |
list_items | read | List products (items) List products/items in the catalog, newest first. Quaderno API: GET /items. Returns item objects (id, code, name, kind, product_type, unit_cost, tax_class, tax_type, currency, stock, …), wrapped as { data, pagination } when more pages exist. |
get_item | read | Get a product (item) Fetch a single product/item by id. Quaderno API: GET /items/{id}. |
list_credit_notes | read | List credit notes List credit notes (refund documents), newest first. Quaderno API: GET /credit_notes. Wrapped as { data, pagination } when more pages exist. |
get_credit_note | read | Get a credit note Fetch a single credit note by id. Quaderno API: GET /credit_notes/{id}. |
list_receipts | read | List receipts List receipts, newest first. Quaderno API: GET /receipts. Wrapped as { data, pagination } when more pages exist. |
get_receipt | read | Get a receipt Fetch a single receipt by id. Quaderno API: GET /receipts/{id}. |
list_expenses | read | List expenses List expenses (bills you received), newest first. Quaderno API: GET /expenses. Wrapped as { data, pagination } when more pages exist. |
get_expense | read | Get an expense Fetch a single expense by id. Quaderno API: GET /expenses/{id}. |
list_tax_codes | read | List tax codes List the product tax codes Quaderno supports (id, name, description) — used as the tax_code on products / tax calculations. Quaderno API: GET /tax_codes. |
list_jurisdictions | read | List tax jurisdictions List the tax jurisdictions (id, name, country, region) where the account is registered to collect tax. Quaderno API: GET /jurisdictions. |
list_webhooks | read | List webhooks List the account's configured webhooks (id, url, events). Quaderno API: GET /webhooks. |
quaderno_request | read | Raw read request Power-user escape hatch: GET any Quaderno API path not wrapped by a dedicated tool. READ-ONLY — only GET is allowed. Path is taken after /api (e.g. "/tax_ids", "/evidence"). Quaderno API: GET {path}. |
create_contact | write | Create a contact MUTATES Quaderno data — create a contact (customer or vendor). Provide kind plus a name; use `fields` for any other Quaderno contact attribute (phone_1, region, postal_code, city, street_line_1/2, tax_status, language, discount, notes, processor/processor_id). Quaderno API: POST /contacts. Returns the created contact. |
update_contact | write | Update a contact MUTATES Quaderno data — update an existing contact. Only the fields you pass are changed; use `fields` for any attribute not typed here. Quaderno API: PUT /contacts/{id}. Returns the updated contact. |
create_item | write | Create a product (item) MUTATES Quaderno data — create a product/item in the catalog. Provide name + unit_cost; use `fields` for any other attribute (code, description, tax_class, tax_type, currency, country, stock). Quaderno API: POST /items. Returns the created item. |
create_invoice | write | Create an invoice MUTATES Quaderno data — create an invoice for a contact. Provide contact_id (or a contact via `fields`) and items; use `fields` for any other attribute (currency, issue_date, due_date, po_number, notes, tag_list, custom_metadata, payment_details). Each item = { description, quantity, unit_price, tax_1_name?, tax_1_rate?, discount_rate?, … }. Quaderno API: POST /invoices. Returns the created invoice (incl. permalink, pdf). |
create_transaction | write | Create a transaction MUTATES Quaderno data — record a sale or refund transaction (Quaderno computes tax and produces the compliant document). Provide the customer, items, and payment. Use `fields` for any other attribute (date, currency, shipping_address, evidence, processor, processor_id, processor_fee_cents, exchange_rate, po_number, notes, tags, custom_metadata). Quaderno API: POST /transactions. Returns the created invoice/credit-note object. |
quaderno_usage_status | Usage status (free-tier meter) Report the caller's current free-tier usage this month: calls used, monthly limit, remaining, and whether the cap is reached. Read-only; does not count against the meter. | |
quaderno_request_feature | Request a missing feature Tell usefulapi that the user needs something the Quaderno tools cannot do yet (a missing tool, field or filter). Call it only when the user asks for something none of the tools can do, and tell the user that you send the request. Do not call it for errors or for normal requests. Do not include personal data, credentials or customer records. Stored with the product name and the client type (for example Claude or Cursor), without the user's account. At most 5 requests per day. Does not count against the meter. | |
quaderno_upgrade | Upgrade to Pro (unlimited) Subscribe to the Pro plan for UNLIMITED Quaderno tool calls (the free tier caps monthly usage). Choose monthly ($9/month) or yearly ($90/year — 2 months free) billing. Returns a Stripe Checkout link to open in your browser; after payment your account upgrades automatically. Does not count against the meter. | |
quaderno_cancel_subscription | Cancel the Pro subscription Cancel the caller's Quaderno Pro subscription at the end of the paid period (no refund for the current period; unlimited calls continue until then, then the free tier applies). Requires confirm: true. Run quaderno_upgrade later to undo the cancel before the period ends. Does not count against the meter. |
| Plan | Price | Limit |
|---|---|---|
| Free | $0 | 100 tool calls / month |
| Pro | $9/mo · $90/yr | Unlimited |
Pro covers this Quaderno server only. Subscribe with quaderno_upgrade (it returns a Stripe Checkout link). Cancel any time with quaderno_cancel_subscription: Pro continues to the end of the paid period, with no refund for the current period, and running quaderno_upgrade before then undoes the cancel. Or write to [email protected].
No. usefulapi is an independent service. It is not affiliated with or endorsed by Quaderno. The server calls the Quaderno API with your own Quaderno access, so it sees only the data that your account can see.
The login page asks for your Quaderno API key and Account subdomain. See Before you connect for where to find them.
No. Add only the URL. Do not add an Authorization header or an API key to the client config. The server signs you in with OAuth: the login page asks for your Quaderno API key and Account subdomain. If the config has such a header, remove it: some clients then send that header instead of the login token, and every call fails with 401.
The login stores them encrypted in the authorization grant of your connection. The server uses them to call the Quaderno API for you and to derive a private account id for usage metering. usefulapi does not show them on any page or in any reply. To stop all access, remove the connector and change or delete these credentials in Quaderno.
Yes, if you approve it. 5 of the 23 Quaderno tools can create or change data. The other 18 are marked read-only. Most MCP clients ask you to approve a tool call before it runs.
The Free plan gives 100 tool calls / month. Pro costs $9/mo or $90/yr, with unlimited tool calls, for this Quaderno server only. Run quaderno_usage_status to see how many calls you used.
Ask the AI to run quaderno_upgrade: it returns a Stripe Checkout link. To cancel, run quaderno_cancel_subscription. Pro continues to the end of the paid period.
Tell the AI what you wanted to do. It can send the request with quaderno_request_feature. We store the text with the server name, the type of AI client and the tool you tried, not with your account, and read every request when we plan new tools. You can send up to 5 requests per day.
Any client that supports remote MCP servers (Streamable HTTP) with OAuth login: Claude (web and desktop), Claude Code, Cursor, VS Code, Windsurf and others.
This is a Model Context Protocol endpoint — meant to be connected from an AI client, not opened in a browser. An invalid_token response at the URL is the auth gate working as designed; clients authenticate automatically.