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A single server.run() call starts your server on stdio (the default) or Streamable HTTP: 
await server.run()                                  // fully env-driven, stdio default
await server.run({ transport: 'http' })             // transport fixed; port/host from env
await server.run({ transport: 'http', port: 3000 }) // fully explicit
This page is under construction. The outline below sketches what it will cover.
  • Configuration priority — code > environment variables > defaults, so a deployed server switches transports with env vars alone: MCP_TRANSPORT, MCP_HOST, MCP_PORT, MCP_PATH (plus plain PORT as a fallback for Railway/Render/Heroku). Defaults: stdio, port 3000, host 0.0.0.0, path /mcp.
  • Transports — stdio and http (Streamable HTTP). SSE is not supported; Streamable HTTP supersedes it.
  • Inspecting the bound address — server.address after run() resolves (including OS-assigned ports with port: 0); null for stdio.
  • Running via the CLI — fastmcp run server.ts and the dev inspector loop.