Meet MCP

Open the fictional practice server in MCP Inspector and identify what it exposes, separating inspection from action before any AI model is involved.

By the end

Explain the basic purpose of MCP in ordinary language
Distinguish the AI application from the MCP server it connects to
Open the fictional practice server in MCP Inspector
Identify what the server exposes without letting an AI use it
Separate inspection from action

Two halves of every MCP setup

Almost every confusion about MCP comes from blurring two separate things.

On one side is the AI application you are working in. On the other is the system it connects to. They are different programs, usually written by different people, often owned by different organizations. MCP is the agreement that lets them talk.

Keeping them separate is what makes the rest of this tutorial possible. If they are one blurry thing, you cannot ask who is allowed to do what. Once they are two things, you can.

Three words to learn

Host

The AI application or environment where you are working.

MCP server

A program or service that exposes capabilities through MCP.

Connection

The link that allows a host or inspection tool to communicate with an MCP server.

“Server” does not mean a machine in a data center. An MCP server is simply a program that offers capabilities. The one you are about to run is a small file sitting in a folder on your own computer.

Step 1 — Check that you have Node.js

The practice server runs on Node.js, a free program for running JavaScript outside a browser. Open your terminal — on a Mac, that is the app called Terminal — and type:

Command

node --version

If it prints a number like v22.19.0 or higher, you are ready. If the command is not found, or the number is lower, install the current LTS release from nodejs.org (opens in a new tab) and try again.

Step 2 — Move into the practice folder

In the same terminal, type cd, then a space, then drag the unzipped mcp-practice folder onto the terminal window. Your computer fills in the location for you. Press Return.

Everything from here happens inside that folder.

Step 3 — Install what the server needs

Command

npm install

This downloads the code the practice server depends on, including the inspection tool you are about to use. It takes a few seconds and prints a summary when it finishes. This is the only step that uses the internet.

Step 4 — Open the MCP Inspector

MCP Inspector is the official tool for looking at an MCP server directly. It is not an AI application, and there is no model behind it. It simply connects to a server and shows you what that server says it offers — which is exactly what we want first.

Command

npm run inspect

The terminal prints a web address containing a one-time token, then opens it in your browser. If it does not open automatically, copy the printed address exactly rather than typing localhost from memory — without the token, the page will not work.

Leave the terminal running. It is running the Inspector. Closing it closes the Inspector. When you are finished, press Ctrl+C there to stop.

Step 5 — Connect

The Inspector opens on its Servers screen with one server listed: practice-resource-desk, marked Disconnected. Beside that status is a toggle switch. Click it.

The status changes to Connected, and three new tabs appear along the top: Tools, Prompts, and Resources.

MCP Inspector connected to the fictional practice-resource-desk server. The server row shows the status Connected with its toggle switch turned on, a STDIO transport, and the command node server.js. Tabs across the top read Servers, Tools, Prompts, Resources, Protocol, and Console. — The practice server, connected. The tabs across the top are the capabilities it exposes. This capture hides the Inspector’s monitoring sidebar, which moves **Protocol** and **Console** into the tab bar; with the sidebar open, as it is by default, you will see four tabs and a panel of protocol traffic on the right. Open full-size image: the Inspector's first connection to the practice server (opens in a new tab)

Those tabs are the whole point. The Inspector shows a Tools tab only because this server offers tools, a Resources tab only because it offers resources, and a Prompts tab only because it offers prompts. A server that offered none of them would show none of those tabs.

Activity — Look before you use

Click through the three capability tabs. Read, but do not run anything yet. Calling the tool comes in the next module, once you know what you are looking at.

Answer these from the screen in front of you

Which server are you connected to, and what launched it?
What are the names of the capabilities it exposes?
Can you tell which are tools, which are resources, and which are prompts?
Which one looks capable of performing an action, rather than just handing back information?
How much could you learn about this server without invoking anything at all?

You should find exactly one of each: a tool named search_resources, a resource describing the desk, and a prompt template for planning a research session. The tool's description says it is read-only.

That last point deserves a note. The server declares that its tool is read-only. That declaration is a claim made by whoever wrote the server, not a guarantee enforced by MCP. On a practice server written for a tutorial, the claim is true. On a server you did not write, a claim is a claim.

What to notice

You have not asked an AI model to do anything.

You connected directly to the practice MCP server and inspected what it says it can provide. No model chose what to show you, summarized it, or decided which capability was worth mentioning.

That is an important habit: understand the connection before delegating through it.

Good MCP habit. When someone offers you an MCP connection, ask what it exposes before you attach it to an AI application. The answer is usually a short list, and you are entitled to see it.

Checkpoint

You are ready for Module 2 if you can:

explain what MCP is for without simply expanding the acronym;
describe the difference between the host and the MCP server;
start the practice server and connect to it in the Inspector;
list the capabilities it exposes and say which kind each one is; and
explain why inspecting is not the same as invoking.

You still have not run a single tool. That is the right place to be.