CLI and MCP show up in the same sentence a lot, usually when somebody’s explaining how they got an AI to do something outside the chat box. They sound related. They’re both plumbing, sure, but one is how you talk to a computer and the other is how a model talks to your software.
CLI
Command line interface. You type a command, hit enter, the computer does the thing. No buttons, no windows, no mouse. The version sitting in your terminal right now isn’t that different from the Unix shell people were using in the 1970s (genuinely, a lot of the commands are the same ones).
A lot of the stronger AI tools are CLI tools. Claude Code runs there. So does OpenAI’s Codex CLI. You install them and run them from a terminal inside whatever folder you’re working in. That’s not nostalgia. Text is cheap to script and easy for a model to read, and a terminal gives an AI tool a direct line to your actual files.
If you’ve never opened a terminal, this is usually where people stall out. The blinking cursor is a real barrier and nobody should pretend otherwise.
MCP
Model Context Protocol. Anthropic released it as an open standard in November 2024, and OpenAI and Google both added support the year after. It’s a shared way for AI models to reach outside tools and data: your Drive, a database, GitHub, whatever project tracker your team argues about.
Before it, every AI app had to build its own custom connection to every service it wanted to touch, which gets ugly fast. MCP is one plug shape everybody can build against instead.
You don’t really use MCP. It runs underneath. When you ask Claude what’s on your calendar and it actually knows, an MCP server is the reason. Most of the time you set it up once from a menu and then forget it exists, which is sort of the goal, and also why the security questions around it are worth paying attention to.
The tell
Ask who’s typing.
A human typing a command and hitting enter is a CLI. A model reaching out to a piece of software on its own, with nobody typing anything, is MCP.
They tangle in practice, because installing an MCP server usually means typing a command into a terminal. So the two do sit next to each other on your screen fairly often.