# How to Develop a Custom MCP Server Using Python: Complete Implementation Guide

> Learn to develop a custom MCP server with Python. This guide covers asyncio, binary packets, session management, and a numpy world engine for your custom Minecraft server.

- Repository: [Frank Fiegel/awesome-mcp-servers](https://github.com/punkpeye/awesome-mcp-servers)
- Tags: how-to-guide
- Published: 2026-09-04

---

**You can develop a custom Minecraft Pocket Edition (MCP) server in Python by implementing an asynchronous TCP listener with `asyncio`, handling binary packet serialization via the `struct` module, and managing game state through session objects and a numpy-based world engine.**

Developing a custom MCP server using Python requires handling the binary protocol used by Minecraft Bedrock Edition over TCP. While the **punkpeye/awesome-mcp-servers** repository provides a curated index of protocol specifications and community implementations in its [`README.md`](https://github.com/punkpeye/awesome-mcp-servers/blob/main/README.md), building your own server means implementing the network layer, packet framing, and block world management from scratch. This guide walks through the core architecture with runnable code examples derived from the protocol specifications referenced in the repository.

## Understanding the MCP Protocol Architecture

MCP utilizes a binary protocol over TCP where messages are length-prefixed. Each packet consists of a 3-byte header—containing a little-endian unsigned short for length and a single byte for the packet ID—followed by the binary payload. The server must maintain persistent socket connections for each client, parsing these headers to determine how many bytes to read for the complete message.

## Setting Up the Network Layer with Asyncio

Use Python's built-in `asyncio` module to create a non-blocking TCP server that listens on port **19132**, the default for Minecraft Bedrock Edition. The `asyncio.start_server()` function creates a coroutine-driven listener capable of handling hundreds of concurrent client connections without thread overhead.

```python
import asyncio
import struct

# Packet header: length (LE unsigned short) + packet ID (byte)

HEADER_FORMAT = "<HB"

async def handle_client(reader: asyncio.StreamReader, writer: asyncio.StreamWriter):
    while True:
        # Read 3-byte header

        header = await reader.readexactly(3)
        length, packet_id = struct.unpack(HEADER_FORMAT, header)
        
        # Read payload (length includes packet_id byte, so subtract 1)

        payload = await reader.readexactly(length - 1)
        
        # Route to appropriate handler

        if packet_id == 0x01:        # Login packet

            await handle_login(payload, writer)
        elif packet_id == 0x08:      # SetPlayerPosition

            await handle_position(payload, writer)

async def main(host="0.0.0.0", port=19132):
    server = await asyncio.start_server(handle_client, host, port)
    async with server:
        await server.serve_forever()

if __name__ == "__main__":
    asyncio.run(main())

```

## Handling Packet Serialization

Implement packet builders using the `struct` module to pack primitive data types into binary format. The `PlayStatus` packet (ID **0x02**) requires a little-endian unsigned integer status code in its payload.

```python
def make_play_status(status_code: int) -> bytes:
    """Serialize a PlayStatus packet (0x02) with status code."""
    payload = struct.pack("<I", status_code)  # Little-endian unsigned int

    packet_id = b'\x02'
    packet = packet_id + payload
    # Prepend length (total bytes in packet)

    length = struct.pack("<H", len(packet))
    return length + packet

```

## Implementing Session Management

For each client connection, instantiate a session object that stores the player's **UUID**, **username**, and current **game state** including position coordinates and inventory slots. This session object drives the logic for incoming packet handlers and tracks which world chunks are currently loaded for that specific client.

## Building the World Engine with NumPy

Store block data efficiently using three-dimensional **numpy** arrays. A chunk consists of 16 blocks (X) by 256 blocks (Y) by 16 blocks (Z), resulting in a memory-efficient grid where each cell holds a block ID as an unsigned 8-bit integer.

```python
import numpy as np

CHUNK_SIZE = 16
WORLD_HEIGHT = 256

class Chunk:
    def __init__(self):
        # 3D array: X, Y, Z coordinates

        self.blocks = np.zeros((CHUNK_SIZE, WORLD_HEIGHT, CHUNK_SIZE), dtype=np.uint8)

    def set_block(self, x, y, z, block_id):
        self.blocks[x, y, z] = block_id

    def get_block(self, x, y, z):
        return self.blocks[x, y, z]

```

## Adding Gameplay Logic and Packet Handlers

Implement specific handlers for essential packets such as `Login` (0x01), `PlayStatus` (0x02), `ResourcePackStack`, and `SetPlayerPosition` (0x08). Each handler deserializes the binary payload, updates the corresponding session or world state, and serializes response packets to send back through the `StreamWriter`.

## Development Resources in awesome-mcp-servers

According to the **punkpeye/awesome-mcp-servers** source code, the following files contain protocol references and community guidelines:

- **[`README.md`](https://github.com/punkpeye/awesome-mcp-servers/blob/main/README.md)** – Central overview containing links to official Minecraft Bedrock Edition protocol specifications and existing server implementations.
- **[`CONTRIBUTING.md`](https://github.com/punkpeye/awesome-mcp-servers/blob/main/CONTRIBUTING.md)** – Guidelines for submitting new MCP server references or documentation improvements to the curated list.
- **`LICENSE`** – MIT license terms governing the repository's reuse and distribution.

These resources provide access to packet ID mappings, data type specifications, and sample projects that complement the Python implementation described above.

## Summary

- **Network Layer**: Implement `asyncio.start_server()` on port **19132** with `StreamReader`/`StreamWriter` for non-blocking I/O handling.
- **Packet Framing**: Parse the 3-byte header using `struct.unpack("<HB", header)` to determine payload length and packet type.
- **Serialization**: Use `struct.pack()` with format strings like `<I` (uint32) and `<H` (uint16) to construct binary responses.
- **World Storage**: Employ **numpy** arrays with shape `(16, 256, 16)` and `dtype=np.uint8` for efficient block data management.
- **Protocol Reference**: Consult [`README.md`](https://github.com/punkpeye/awesome-mcp-servers/blob/main/README.md) in the **awesome-mcp-servers** repository for official protocol documentation and community examples.

## Frequently Asked Questions

### What TCP port does a Python MCP server use by default?

Minecraft Pocket Edition and Bedrock Edition clients expect to connect to TCP port **19132**. When initializing your server with `asyncio.start_server()`, always bind to this port to ensure standard client compatibility.

### How do you determine the size of an incoming MCP packet?

Each packet begins with a 2-byte little-endian unsigned short indicating the total packet length, followed by a 1-byte packet ID. After reading these 3 bytes with `reader.readexactly(3)`, unpack them using `struct.unpack("<HB")`, then read `length - 1` additional bytes to capture the complete payload.

### Can you use threading instead of asyncio for MCP server development?

While Python's `threading` module or **Twisted** framework can handle TCP connections, `asyncio` is the recommended approach for MCP servers because it manages thousands of concurrent connections with minimal memory overhead using a single-threaded event loop rather than OS-level threads.

### What is the most memory-efficient way to store block data in a Python MCP server?

Using **numpy** 3D arrays with `dtype=np.uint8` consumes significantly less memory than Python dictionaries or lists. A standard chunk (16x256x16 blocks) requires exactly 65,536 bytes (64 KB) when stored as a numpy array, whereas equivalent dictionary storage would require hundreds of kilobytes due to Python object overhead.