MCP and AI basics
stdio
A transport where the host starts the MCP server as a local process and talks to it through standard input and output. Typical for servers you install and run on your own computer.
stdio (standard input and output) is the transport for MCP servers that run as a local process. The host application starts the server with a command, sends it JSON-RPC messages on its input and reads replies from its output. Nothing goes over the network between client and server, although the server itself will call the vendor's API.
Google's open-source servers for Google Ads and Google Analytics are the common e-commerce examples. You install a runtime such as Node.js or Python, run the server with your own credentials and point a desktop or terminal client at it. That makes stdio servers a natural fit for a technical person at an agency and a poor fit for a merchant who only uses a browser.
The trade-off is control versus convenience. You own the credentials and can inspect exactly what the server does, but you also maintain it, keep its keys safe and update it. If a vendor offers both a local and a hosted server, start with the hosted one unless you need the control.