MCP
PickModel Context Protocol: a standard plug that lets an AI assistant use your tools and data without custom integration work.
01 · Introduction
What MCP is
Think of a USB port. Any device with the right plug works with any computer. MCP (Model Context Protocol) is that plug for AI assistants.
An MCP server is a small program that exposes something useful: your files, a database, a calendar, a company wiki, a web search. An MCP client is the assistant that uses it: Claude, Claude Code, Cursor, and many others.
Once a server exists, every client that speaks MCP can use it. Before MCP, each assistant needed its own integration for each tool.
A server offers three kinds of things: tools (actions the assistant can call), resources (data it can read) and prompts (ready-made instructions).
02 · When to use it
When to use it
- You want Claude to read files in a project folder, or your notes app, while you chat.
- Your team has an internal system (a ticket tool, a database) and you want assistants to query it safely.
- You use several AI tools and are tired of configuring the same integration in each one.
- You are building a product and want other people's assistants to work with it.
You do not need MCP for a one-off task you can paste into a chat.
03 · Setup
Connecting your first server
The quickest start is Claude Desktop with the filesystem server:
- Install Node.js if you do not have it.
- Open Claude Desktop → Settings → Developer → Edit Config.
- Add a server entry that points at a folder you allow:
{
"mcpServers": {
"files": {
"command": "npx",
"args": ["-y", "@modelcontextprotocol/server-filesystem", "/Users/you/Documents/agents"]
}
}
}
- Restart Claude Desktop. A tools icon appears; ask "list the files in my agents folder".
Many services now publish a hosted MCP server you connect with a URL and a login instead of a local command.
04 · How to use it
Day-to-day use
- Ask in plain language; the assistant decides which tool to call and asks before anything that changes data.
- Keep the list of connected servers short. Each one adds instructions the model must read on every turn.
- Prefer read-only servers until you trust the setup; add write access tool by tool.
- When a tool call fails, the error text is usually in the assistant's reply. Read it before retrying.
05 · Pitfalls
Pitfalls
- A server runs with your permissions. A filesystem server pointed at your home folder can read everything in it. Point it at one folder.
- Trust the publisher. Install servers from the vendor or the official list, not from a random repository.
- Prompt injection. Data a server returns (a web page, a document) can contain text that tries to give the assistant orders. Treat tool output as data, not instructions.
- Local servers need Node.js or Python installed and stop when the app closes; hosted servers do not.
06 · Resources
Where to go next
The specification is readable even if you never build a server; the quickstarts are the fastest way to see it work.
