FrankKi

What the FrankKi MCP server does

The FrankKi MCP server gives software access to FrankKi’s physical mail service. An agent can provide letter content and recipient details, while FrankKi formats, prints, franks, and sends the document through postal partners in the destination country. Delivery is available worldwide.

The service is aimed at B2B workflows, assistants, backends, and other automations whose final step cannot remain digital. Examples include payment reminders, cancellations, contract confirmations, account notices, welcome letters, and compliance-related correspondence.

Composition is text-first. The platform creates a formatted letter, using DIN 5008 by default, rather than accepting an arbitrary pre-rendered PDF as the primary input. Attachments are supported.

How it works

The server is a hosted remote MCP endpoint at https://mcp.frankki.app. It uses streamable HTTP and exposes its current tool inventory through the MCP tools/list method. The repository contains documentation and a public manifest; the server implementation is closed-source and runs on FrankKi infrastructure.

Interactive clients can authenticate with OAuth 2.1. Headless applications can send a bearer API key instead. A prepaid wallet funds sends, and a sandbox is available for testing without mailing real items. Sending tools have external side effects: they charge the wallet and cause physical mail to be dispatched.

A typical workflow validates or finds an address, drafts a letter, previews or prices it, checks available funds, and then sends it. Applications can also submit a letter for four-eyes approval, schedule sends, or inspect order status after dispatch.

Setup and configuration

There is no package to install and no local process to self-host. Configure an MCP client with the remote URL, then authenticate through its OAuth flow or provide a static bearer key for headless use. Clients that require stdio can connect through the documented mcp-remote bridge.

Claude Code can register the endpoint with its HTTP transport. For programmatic clients, the repository documents TypeScript and Python streamable-HTTP connections. The OAuth authorization-server metadata is published at https://mcp.frankki.app/.well-known/oauth-authorization-server.

Before production use, create a partner account, issue an API key if needed, and fund the prepaid wallet. The sandbox should be used when a workflow needs testing without real delivery.

Tools and capabilities

Core tools include:

• address_validate checks a recipient address against destination-country postal rules.
• address_search_company looks up a company’s postal address.
• template_list lists reusable letter templates.
• letter_create_draft creates a formatted draft and returns a preview without sending it.
• shipping_quote returns the price before commitment.
• wallet_balance reads the prepaid balance.
• order_send sends one letter and supports a maximum-cost guard.
• order_send_batch sends to multiple recipients using merge fields.
• approval_submit places a letter in an approval queue instead of sending immediately.
• order_status reports progress through printing, posting, and delivery.
• wallet_topup_link creates a Stripe payment link for wallet funding.

Additional capabilities cover attachments, letterheads, signatures, sender profiles, presets, scheduling, cancellation, posting receipts, client lookups, and GoBD/DATEV archive exports. The authoritative tool list is the one returned by the live server.

Limitations and notes

FrankKi MCP server is remote and closed-source, so it is not suitable for users seeking a self-hosted implementation. Direct sends spend wallet funds and mail physical documents; applications should use previews, quotes, approval routing, or the maxCostEuros guard where human confirmation is required.

The platform is designed around text-based letter composition. Sending an arbitrary pre-rendered PDF is intentionally not supported as the main document workflow. Delivery is handled by postal partners, and order status can be used to follow the item after submission.