---
title: "stdio transport: definition and example | Agent MCP Directory"
description: "stdio transport: The MCP binding where a client launches the server as a subprocess and exchanges newline-delimited JSON-RPC over."
canonical: https://agentmcpdirectory.com/glossary/stdio-transport
site: "Agent MCP Directory"
last_updated: 2026-11-04
section: "Glossary"
---

# stdio transport: definition and example | Agent MCP Directory

> stdio transport: The MCP binding where a client launches the server as a subprocess and exchanges newline-delimited JSON-RPC over.

Source: https://agentmcpdirectory.com/glossary/stdio-transport
Site: Agent MCP Directory
Last reviewed: 2026-11-04

# stdio transport

stdio transport: The MCP binding where a client launches the server as a subprocess and exchanges newline-delimited JSON-RPC over standard streams. Example: Apify's local server runs with npx @apify/actors-mcp-server over stdio. Next in the glossary is Step-up authorization: Requesting a wider scope set after a 403 insufficient\_scope challenge, keeping previously granted scopes.

## Definition

The MCP binding where a client launches the server as a subprocess and exchanges newline-delimited JSON-RPC over standard streams.

## Example, with source

Apify's local server runs with npx @apify/actors-mcp-server over stdio. ([docs.apify.com](https://docs.apify.com/platform/integrations/mcp), read 4 November 2026)

## Where it appears on this site

-   [MCP](https://agentmcpdirectory.com/standards/mcp/)
-   [Building a remote MCP server](https://agentmcpdirectory.com/guides/build-remote-mcp-server-cloudflare-vercel/)

## Neighbouring terms

-   [Stateless MCP](https://agentmcpdirectory.com/glossary/stateless-mcp/): The 2026-07-28 model with no initialize handshake and no Mcp-Session-Id; each request carries version and capabilities in \_meta.
-   [Step-up authorization](https://agentmcpdirectory.com/glossary/step-up-authorization/): Requesting a wider scope set after a 403 insufficient\_scope challenge, keeping previously granted scopes.
-   [Streamable HTTP](https://agentmcpdirectory.com/glossary/streamable-http/): The MCP HTTP binding where each message is a POST to one endpoint and replies come as JSON or a request-scoped SSE stream.

Edition

4 November 2026

Method

[How rows are verified](https://agentmcpdirectory.com/method/)

Data

[CSV and JSON](https://agentmcpdirectory.com/data/)

Markdown

[This page as markdown](https://agentmcpdirectory.com/glossary/stdio-transport/index.md)

## Sources

-   [Source for the stdio transport example](https://docs.apify.com/platform/integrations/mcp), read 4 November 2026

Last reviewed 4 November 2026