# MCP (Model Context Protocol)

> Part of the AI Garage Jargons glossary: https://aigarage.in/jargons (all terms: https://aigarage.in/jargons.md)

**Category:** LLM
**Tags:** protocol, tools, agents, integration

An open standard for connecting AI applications to external systems, so one application can use tools, data, and prompts from many servers through the same interface.

**In plain terms:** It is a USB-C port for AI apps. Instead of a different cable for every service, the app and the service agree on one plug.

**Use cases:**
- Connecting an assistant to a calendar, files, or a database
- Letting a coding agent use a design tool
- Giving several AI apps the same company data through one server

**Why it matters:** Without a shared standard, every AI app needs a custom integration for every system. With MCP, a server built once can work with any application that supports it. It also moves the important questions to the server and the host: what the tools can do, who may call them, and what a person must approve.

**Why now:** Anthropic open-sourced MCP in November 2024, and the project's documentation lists support across many AI assistants and developer tools. The specification is still evolving, and a recent version changed how connections and discovery work, so check the current specification before relying on a detail.

**AI Garage example:** AI Garage runs a remote MCP connector that people can add to an AI assistant such as Claude. Connecting requires signing in, and an unauthenticated request is refused. Through it, an assistant can use AI Garage's tools without anyone opening the website. The server runs separately from this website's code.

**Mental model:** MCP is a shared language between an AI application, the host, and the programs that provide context, the servers. The host keeps one client connection per server. Each server tells the client what it offers: tools the model can call, resources to read, and prompt templates. The host offers those tools to its model, and the model's calls go through the client to the server. MCP covers the connection, not the model's reasoning or what the application does with the results.

**Builder scenario: Connect one system to many AI apps without rewriting it**

- **Context:** A team wants assistants in two different AI apps to read the same project notes and create tasks in the same tracker.
- **Failure:** They write a separate custom integration for each app. Each behaves slightly differently, and any change to the tracker means fixing both.
- **Intervention:** Build one MCP server that exposes a resource for reading notes, a tool for searching notes, and a tool for creating tasks. Mark the task tool as one that changes things, require sign-in, and let each AI app connect to the same server.
- **Outcome:** Both apps list the same tools from one server. A change to the tracker is made once, and the create-task action asks for approval in each app.

**Common misconceptions:**
- **Claim:** MCP is a tool or a model.
  **Correction:** It is a protocol, a set of rules for how an AI application and a server talk. It does not choose tools for the model, run the model, or decide how results are used.
- **Claim:** An MCP server is safe because it follows a standard.
  **Correction:** The standard defines how a connection works, not whether a tool is safe. What a tool can do, who can call it, and what needs a person's approval are decisions for the server and the host.

**Visual model (system):** The host connects to each server through the same standard. What a server can do, and who may use it, is still decided on the server.

**Visual description:** A system map: an AI application (the host) keeps one MCP client per server. Each client connects to an MCP server through a standard connection. The server offers tools, resources, and prompts, and does the work in an external system such as a calendar or a database.

**Related concepts:** [Tool Calling](https://aigarage.in/jargons/tool-calling), [AI Agent](https://aigarage.in/jargons/ai-agent), [API](https://aigarage.in/jargons/api), [Context Window](https://aigarage.in/jargons/context-window), [Agent Skill](https://aigarage.in/jargons/agent-skill), [Human in the Loop](https://aigarage.in/jargons/human-in-the-loop)

**Last researched:** 2026-10-12

**Sources:**
- [Model Context Protocol - What is MCP?](https://modelcontextprotocol.io/docs/getting-started/intro)
- [Model Context Protocol - Architecture overview](https://modelcontextprotocol.io/docs/learn/architecture)
- [Anthropic - Introducing the Model Context Protocol](https://www.anthropic.com/news/model-context-protocol)

**URL:** https://aigarage.in/jargons/mcp