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Use stdio when the MCP client launches your server as a local command and communicates through stdin and stdout.

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Start the stdio transport

import { Redop } from "@redopjs/redop";

new Redop({
  serverInfo: {
    name: "stdio-server",
    version: "0.1.0",
  },
})
  .tool("ping", {
    handler: () => ({ pong: true }),
  })
  .listen({
    transport: "stdio",
  });

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Run it

bun run src/index.ts
Your MCP host should launch that command and then talk to the process over stdio.

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Keep stdout clean

Do not write logs to stdout in stdio mode. Stdout is the MCP message channel. Send diagnostic output to stderr instead.

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Use stdio when

  • local desktop MCP clients
  • editor integrations that launch a command directly
  • tools that do not need a long-running network service