Example apps

Simple MCP Server

This example demonstrates how to build a minimal custom MCP (Model Context Protocol) server from scratch using FastMCP 2.0.

This is a great starting point for building your own custom MCP servers with business-specific tools and logic.

Running on Unikraft Cloud

To run this MCP server on Unikraft Cloud:

Install the unikraft CLI. You need a BuildKit builder. The easiest way to get one is via Docker. Alternatively, you can also directly set up and use BuildKit, see the quick start.

Clone the examples repository and cd into the examples/mcp-server-simple/ directory:

Code
git clone https://github.com/unikraft-cloud/examples
cd examples/mcp-server-simple/

Make sure to log into Unikraft Cloud and pick a metro close to you. This guide uses fra (Frankfurt, 🇩🇪):

Code
unikraft login

When done, invoke the following command to deploy this app on Unikraft Cloud:

Code
unikraft build . --output <my-org>/mcp-server-simple:latest
unikraft run --metro fra \
  -m 512M \
  -p 443:8080/tls+http \
  --scale-to-zero policy=on,cooldown-time=1000,stateful=true \
  --image <my-org>/mcp-server-simple:latest

The output shows your instance details:

Code
metro:        fra
name:         mcp-server-simple-bbdcb
uuid:         e87d3591-3497-4f30-bd76-1dc886059647
state:        starting
image:        <my-org>/mcp-server-simple
resources:
  memory:     512MiB
  vcpus:      1
service:
  uuid:       3cfc78af-748d-c6ba-5bfb-427b3bd7e9aa
  name:       cool-paper-b6mht7jv
  domains:
  - fqdn:     cool-paper-b6mht7jv.fra.unikraft.app
networks:
- uuid:       6a712117-5b67-d89a-7e2e-4a57e1732724
  private-ip: 10.0.0.193
  mac:        12:b0:39:2b:a3:15
timestamps:
  created:    just now

In this case, the instance name is mcp-server-simple-bbdcb and the service cool-paper-b6mht7jv. They're different for each run.

For testing, you can use the example client included in this directory. First, install uv if you haven't already, then run:

Code
export MCP_SERVER_URL=https://cool-paper-b6mht7jv.fra.unikraft.app/mcp
uv run client.py

Code
Connecting to https://cool-paper-b6mht7jv.fra.unikraft.app/mcp...

--- Listing Tools ---
Name: get_weather
Description: Get current weather for a city.

Args:
    city: Name of the city

Returns:
    Weather information including temperature, conditions, and humidity

Name: get_time
Description: Get current time in a timezone.
...

You can list information about the instance by running:

Code
unikraft instances list

Code
METRO  NAME                     STATE    IMAGE                       ARGS  MEMORY  VCPUS  FQDN                                  CREATED
fra    mcp-server-simple-bbdcb  standby  <my-org>/mcp-server-simple        512MiB  1      cool-paper-b6mht7jv.fra.unikraft.app  2 minutes ago

When done, you can delete the instance with:

Code
unikraft instances delete mcp-server-simple-bbdcb

Available tools

This MCP Server provides the following tools:

get_weather: Get simulated weather for a city
get_time: Get current time in a timezone
calculate: Perform basic arithmetic operations (add, subtract, multiply, divide)

Building your own tools

This example shows the basic structure of an MCP server using FastMCP. To add your own tools:

Define the tool using the @mcp.tool() decorator:
- Add type hints for parameters
- Include a docstring describing what the tool does
- Parameters are automatically converted to JSON schema
Write the tool function:
- Process the parameters
- Return a string result (or raise an exception for errors)

Test locally before deploying:

Code
pip install -r requirements.txt
python server.py

Example:

Code
from fastmcp import FastMCP

mcp = FastMCP("My Custom Server")

@mcp.tool()
def my_custom_tool(param1: str, param2: int) -> str:
    """Description of what this tool does.

    Args:
        param1: Description of first parameter
        param2: Description of second parameter

    Returns:
        Result description
    """
    # Your implementation here
    return f"Processed {param1} with {param2}"

if __name__ == "__main__":
    mcp.run(transport="http", host="0.0.0.0", port=8080)

Architecture

The server uses FastMCP, a high-level framework for building MCP servers that features:

HTTP Transport: Built-in Streamable HTTP transport
Type-Safe: Automatic JSON schema generation from Python type hints
Simple API: Decorator-based tool definitions

This provides:

Standard MCP protocol support
Automatic tool schema generation
Built-in HTTP server
Easy deployment to any platform

Learn more

Use the --help option for detailed information on using Unikraft Cloud:

Code
unikraft --help

Or visit the CLI Reference.

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Last modified on October 5, 2026

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