SumUp MCP Server

SumUp's Model Context Protocol (MCP) server for interactions between large language models (LLMs) and SumUp APIs. The MCP server allows you to connect to SumUp's services from an MCP client (e.g. Cursor, Claude) and use natural language to work with your SumUp account.

This package runs as a Cloudflare Worker and serves the MCP transport for SumUp.

Authentication follows the MCP OAuth resource-server flow:

• The worker publishes protected resource metadata that points clients to the SumUp authorization server.
• Clients send Authorization: Bearer <access-token> to /mcp.
• Bearer tokens must be JWT access tokens issued by SUMUP_AUTH_HOST and valid for the worker resource URL.

SumUp API keys such as sup_sk_... are not valid Bearer tokens for the hosted server.

The worker exposes /mcp for Streamable HTTP and /sse for the legacy SSE transport. Both routes are pinned to a Durable Object so MCP session state survives across requests within the same Worker deployment.

Using from an MCP client

Any client that speaks the Streamable HTTP transport can connect to this server. For example, using mcp-remote:

{
  "mcpServers": {
    "sumup": {
      "command": "npx",
      "args": [
        "mcp-remote",
        "https://mcp.sumup.com/mcp",
        "--headers",
        "Authorization: Bearer <your-access-token>"
      ]
    }
  }
}

Replace <your-access-token> with an OAuth access token issued for the MCP resource. OAuth-capable clients can discover the authorization server from the protected resource metadata instead of requiring a token to be configured manually.

Development

Development setup, local testing, and contributor workflow live in CONTRIBUTING.md.