Choosing a transport

MCP servers speak to clients over a transport. mcpgen generates a server that supports both of the standard ones, and you pick the default at generation time:


npx mcpgenx generate ./openapi.yaml --out ./my-server --transport stdio   # default
npx mcpgenx generate ./openapi.yaml --out ./my-server --transport http

The generated server reads MCPGEN_TRANSPORT at runtime too, so you can switch without regenerating.

stdio

The server runs as a subprocess of the client and talks over stdin/stdout.

Best for: local, single-user setups — Claude Desktop, Cursor, VS Code on your machine.
Auth/network: none needed; the client launches the process directly.
Run: MCPGEN_TRANSPORT=stdio node dist/server.js


// Claude Desktop / Cursor config
{
  "mcpServers": {
    "my-server": { "command": "node", "args": ["/abs/path/dist/server.js"] },
  },
}

Streamable HTTP

The server listens on a port and serves MCP over Streamable HTTP at /mcp, with a /healthz liveness probe.

Best for: remote/shared deployments, or connecting over the network.
Auth/network: terminate TLS at the edge; set CORS and DNS-rebinding protection (below).
Run: MCPGEN_TRANSPORT=http node dist/server.js (defaults to port 3000).


// VS Code (http)
{
  "servers": {
    "my-server": { "type": "http", "url": "http://localhost:3000/mcp" },
  },
}

For any remote HTTP deployment, harden the transport: set MCPGEN_ALLOWED_HOSTS to your public domain(s) to enable DNS-rebinding protection, set MCPGEN_CORS_ORIGIN to your client’s origin (not *), and put TLS in front of it. See Deploying.

Which should I pick?

	stdio	Streamable HTTP
Local, one user	best, simplest	works, more setup
Remote / shared	no	yes
Needs a network port	no	yes (`/mcp`, `/healthz`)
Hardening required	minimal	TLS + CORS + allowed-hosts

When in doubt, start with stdio for local use and switch to http when you deploy.