What an MCP Server Actually Does
A server as a tidy bundle of capabilities for AI clients.
What an MCP Server Actually Does is a free MCP Academy lesson on CoddyKit — lesson 3 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the MCP Academy learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
A Bundle of Skills
An MCP server is a small program that bundles up capabilities and offers them to AI clients in one tidy package. 🎁
It Advertises What It Can Do
When a client connects, the server first advertises its capabilities. The model learns exactly what is on offer before using anything.
Tools: Actions
A tool is an action the model can take, like sending an email or running a query. Tools do things and return a result.
Resources: Data
A resource is read-only data the model can pull in for context, like a file or a record. Resources inform, they do not act.
Prompts: Templates
A prompt is a reusable instruction template the user can trigger, like a ready-made review request. It shapes how the model is asked.
Three Primitives, One Server
Tools, resources, and prompts are the three primitives a server can expose. Most servers mix and match the ones they need.
It Runs Real Code
When the model calls a tool, the server runs your actual code and hands back the output. The model decides; your server does the work.
@mcp.tool()
def add(a: int, b: int) -> int:
return a + bA Clean Boundary
The server is a clear boundary. Your logic and secrets live inside it, while the model only ever sees the capabilities you choose to expose.
Speaks the Protocol
The server talks to clients using MCP's shared protocol. That common language is what lets any compatible client connect.
Small and Focused
Good servers stay focused: one server for files, another for your database. Each is a neat bundle around a single domain.
You Are the Author
You decide what your server exposes and how it behaves. Building one means deciding which capabilities the AI gets to use. 🛠️
Quick Check
Match each primitive to what it provides.
Recap
An MCP server bundles capabilities and advertises them: tools to act, resources to read, and prompts to reuse, all over the shared protocol.
Frequently asked questions
Is the “What an MCP Server Actually Does” lesson free?
Yes — the full text of “What an MCP Server Actually Does” is free to read here on the web, and the MCP Academy course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the MCP Academy course, upgrade to CoddyKit PRO.
What will I learn in “What an MCP Server Actually Does”?
A server as a tidy bundle of capabilities for AI clients. You practise MCP Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start MCP Academy?
No prior experience is required. MCP Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 3 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “What an MCP Server Actually Does” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this MCP Academy lesson?
Yes. Every MCP Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- The Problem: M-by-N Integrations
- MCP as the USB-C for AI
- What an MCP Server Actually Does
- MCP in the Real World Today