Try this first

Count the tool definitions you would need for a genuinely useful assistant: files, git,
GitHub issues, Slack, a database, your calendar, your ticketing system.

Seven integrations. Now count them again for the next agent you build. Fourteen. Now
consider that your colleague is writing their own seven, for the same seven services.

The shape of the problem

This is the M×N problem. M agents, N services, and without a standard you write M×N
integrations.

  before                         after

  agent A ──┬── GitHub           agent A ──┐
            ├── Slack                      ├── MCP ──┬── GitHub server
            └── Postgres                   │         ├── Slack server
                                agent B ──┘         └── Postgres server
  agent B ──┬── GitHub
            ├── Slack
            └── Postgres

With a standard, the GitHub people write one server. Every agent that speaks MCP can use
it. You write M + N instead of M×N, and you write the M part once.

That is the whole idea. MCP is a standard way to describe a menu of tools, so that a menu
written by someone else can be handed to a model by you.

What MCP is not

Three things it is easy to assume and that are wrong:

It is not an AI protocol. There is no model in it. MCP describes tools and delivers
results. What you do with them is your business — you could drive an MCP server from a
command-line script with no model anywhere.

It does not run the model, or make decisions. Your loop from Module 1 is still the loop.
MCP just changes where the tool definitions come from and who executes them.

It is not new machinery. It is JSON-RPC over a pipe. You will see the whole thing in the
next lesson and it will be less than you expect.

Where it sits in what you have

Go back to the four pieces of agent.py from Lesson 1.6:

Piece Without MCP With MCP
Tool definitions You write them The server sends them
Tool implementation Your functions Runs in the server
The loop Yours Still yours
The transcript Yours Still yours

Two of four change. The loop you spent Module 1 on is untouched, which is the reassuring part
of this module.

MCP replaces the menu and the kitchen. It does not replace the loop, and the loop is what
you built.

Try this before the next lesson

List three services you would actually want an agent to reach. For each, write down the two
or three operations you would need.

Keep the list. In Lesson 5.4 you build a server, and it is more satisfying to build one you
would use.

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