fusionauth.io

// npm i @modelcontextprotocol/sdk zod  — minimal remote MCP server (Streamable HTTP, stateless)
import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { StreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/streamableHttp.js";
import express from "express";
import { z } from "zod";

const app = express();
app.use(express.json());

app.post("/mcp", async (req, res) => {
  const server = new McpServer({ name: "fusionauth.io", version: "1.0.0" });
  // One tool per core job. Clear verbs, typed inputs, small outputs.
  server.tool("create_<thing>", "Create a <thing> for the signed-in user.", { name: z.string() },
    async ({ name }) => {
      const key = req.headers.authorization?.replace("Bearer ", ""); // scoped API key or OAuth token
      const r = await fetch("https://fusionauth.io/v1/<things>", { method: "POST", headers: { Authorization: `Bearer ${key}` }, body: JSON.stringify({ name }) });
      return { content: [{ type: "text", text: await r.text() }] };
    });
  const transport = new StreamableHTTPServerTransport({ sessionIdGenerator: undefined });
  res.on("close", () => transport.close());
  await server.connect(transport);
  await transport.handleRequest(req, res, req.body);
});
app.listen(3000);