Connect with Your MCP Client

MCPX is essentially a MCP server, just like any other. Connecting to it using the SDK is similar to any MCP integration. Because MCPX adopts a remote-first approach - that is, it is meant to be deployed on the cloud - it accepts SSE connections and not stdio ones.

You may pass extra headers when constructing a Transport in the client app - the one that will be used in order to connect to MCPX. See Basic API Key Auth and ACL for actual extra headers' use-cases.

const client = new Client({ name: "mcpx-client", version: "1.0.0" });
await client.connect(transport);

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StreamableHttp Transport

This is the recommended way to connect the MCP servers.

const transport = new StreamableHTTPClientTransport(
  new URL(`${MCPX_HOST}/mcp`),
  {
    requestInit: {
      headers: {
        "x-lunar-consumer-tag": process.env["CONSUMER_TAG"] || "anonymous",
        "x-lunar-api-key": process.env["API_KEY"] || "",
      },
    },
  }
);

---

SSE Transport

This transport is in deprecation, however MCPX still support it to maintain backward compatibility for the time being.

const transport = new SSEClientTransport(new URL(`${MCPX_HOST}/sse`), {
  eventSourceInit: {
    fetch: (url, init) => {
      const headers = new Headers(init?.headers);
      const consumerTag = process.env["CONSUMER_TAG"] || "anonymous";
      headers.set("x-lunar-consumer-tag", consumerTag);
      headers.set("x-lunar-api-key", process.env["API_KEY"] || "");
      return fetch(url, { ...init, headers });
    },
  },
});