What Is an MCP Server? A Plain-Language Explanation

An MCP server is a program or online service that gives an AI assistant data and functions under the rules of the Model Context Protocol (MCP), an open standard that Anthropic introduced on 25 November 2024. The assistant connects to the server, reads the list of functions it offers and uses them when needed; the rules say the app asks for your consent before it uses a tool or sends your data to a server.

Updated October 2026. Sources: modelcontextprotocol.io (architecture, server concepts); Anthropic announcement (25 November 2024); MCP blog and Linux Foundation (9 December 2025); documentation from OpenAI, Anthropic, Microsoft and Google (viewed on 13 October 2026).

What is an MCP server?

An MCP server is the part of a connection that offers something: a calendar, a folder of files, a database, a list of promotions. "Server" does not necessarily mean a computer in a data centre. It means a program that can run on your own computer (a local server) or on the internet, run by the provider of the service (a remote server). The project itself compares MCP to a USB-C port for AI applications: one standard plug instead of a different cable for every pair of devices.

Anthropic introduced MCP on 25 November 2024 to replace custom integrations, one per data source, with a single standard. On 9 December 2025 it announced the donation of the project to the Agentic AI Foundation, a fund under the Linux Foundation co-founded by Anthropic, Block and OpenAI: according to the MCP blog, the Linux Foundation provides a neutral home, but the maintainers, who run the project, still make the decisions about the protocol through public proposals. MCP is not an artificial intelligence and not one company’s product: it is a set of rules for exchanging information between an assistant and a service.

How does MCP work, in plain words?

Which AI assistants use MCP?

The steps for ChatGPT and Claude are in the guide to ChatGPT connectors.

A Swiss example: the weekly shop

Imagine a hypothetical service that publishes the weekly promotions of Swiss supermarkets through an MCP server, and an assistant you have connected it to:

1. You ask: "What is on promotion this week for pasta and tomato sauce in the canton of Zurich?"
2. The assistant picks a tool from those the server declares, for example "search promotions by product and canton"; without a standing approval, the app asks for your permission.
3. The server answers with the data it holds for that product and canton: product, shop, validity period.
4. The assistant writes the answer with that data. It did not have it before: it receives it for this question.

Without a server, an assistant answers from what it learned in training or from a web search (see the guide to ChatGPT and supermarket promotions). With a server the data comes from a specific source, updated as its operator decides: check who runs it, which shops it covers and how often it updates. The validity period differs from chain to chain (see the start day of promotions): before you shop, compare the answer with the flyer or with this week’s promotions.

MCP and privacy: what you allow

When you connect a server you allow the connection, what the assistant may do, and the data it sends to the server. According to the MCP specification, the app must get your explicit consent before it sends your data to a server and before it uses a tool, but the protocol cannot enforce that on its own: it depends on the assistant and the server.

• Permissions. For a remote server you usually sign in with your account on the service’s website and see what it asks for, for example read-only or also changing data. Choose the minimum.
• Confirmations. In ChatGPT, write actions of custom MCP servers in developer mode ask for confirmation by default (OpenAI), and OpenAI flags the option that allows all actions as elevated risk. Anthropic advises "Always allow" only for servers you trust.
• Data. In ChatGPT an app can receive the chat context and, with Memory on, memories (OpenAI): do not write anything you would not entrust to its operator. For data in chats see the guide to ChatGPT and personal data.
• Hidden instructions and local servers. Anthropic warns that a malicious server can hide instructions (prompt injection), and OpenAI that untrusted servers raise this risk; the MCP security page warns that a local server can run programs with the same rights as the app. Connect and install only what you trust.

To disconnect: in ChatGPT, according to OpenAI, open Settings > Plugins (or Apps), pick the app and select "Disconnect" in the three-dot menu; in Claude, according to Anthropic, open Customize > Connectors and select "Disconnect" to sign Claude out of the service, or "Remove" in the three-dot menu to take the connector off. Disconnecting does not delete saved chats or memories (OpenAI); if the connected service offers its own way to withdraw access, use it too. If the assistant should also act for you, see the guide to AI shopping agents.

How to try it today

Start with an assistant you already use and a service whose official page explains how to connect it; at first, pick a connection that can only read.

1. Choose a harmless task, such as a test calendar, and not your bank account or your work email.
2. Find the server’s address on the service provider’s official page, not in an anonymous post.
3. Add the connector in the assistant’s settings, if your plan allows it: the steps are in the guide to ChatGPT connectors.
4. Read the permissions at sign-in and decline the ones you do not need.
5. Ask a simple question, watch which tools the assistant wants to use, and disconnect the connector when you are done.

For groceries you can also start without any connector: Rappn is a free Swiss app (iOS and Android) that compares the current promotions of seven Swiss retailers and turns receipts into a spending overview. The promotions are updated daily as the chains publish them; you can filter them by canton, put products on a list that shows an estimated price (prices are indicative) and get an alert when a product you follow goes on offer. Rappn covers groceries only, not rent, insurance or taxes, and has no subscription. Rappn is building an AI assistant for groceries: you can join the waitlist. A Rappn connector for AI assistants is in development.