csharp

Basic Calculator MCP Service

This service provides basic calculator operations through the Model Context Protocol (MCP). It's designed as a simple example for beginners learning about MCP implementations.

For more information, see C# SDK

Features

This calculator service offers the following capabilities:

1. Basic Arithmetic Operations:
   • Addition of two numbers
   • Subtraction of one number from another
   • Multiplication of two numbers
   • Division of one number by another (with zero division check)

Using stdio Type

Configuration

1. Configure MCP Servers:

   • Open your workspace in VS Code.

   • Create a .vscode/mcp.json file in your workspace folder to configure MCP servers. Example configuration:

     {
       "inputs": [
         {
           "type": "promptString",
           "id": "repository-root",
           "description": "The absolute path to the repository root"
         }
       ],
       "servers": {
         "calculator-mcp-dotnet": {
           "type": "stdio",
           "command": "dotnet",
           "args": [
             "run",
             "--project",
             "${input:repository-root}/03-GettingStarted/samples/csharp/src/calculator.csproj"
           ]
         }
       }
     }

   • You will be asked to enter the GitHub repository root, which can be fetched from the command, git rev-parse --show-toplevel.

Using the Service

The service exposes the following API endpoints through the MCP protocol:

• add(a, b): Add two numbers together
• subtract(a, b): Subtract the second number from the first
• multiply(a, b): Multiply two numbers
• divide(a, b): Divide the first number by the second (with zero check)
• isPrime(n): Check if a number is prime

Test with Github Copilot Chat in VS Code

1. Try making a request to the service using the MCP protocol. For example, you can ask:
   • "Add 5 and 3"
   • "Subtract 10 from 4"
   • "Multiply 6 and 7"
   • "Divide 8 by 2"
   • "Does 37854 prime?"
   • "What are the 3 prime numbers before after 4242?"
2. To make sure it's using the tools add #MyCalculator to the prompt. For example:
   • "Add 5 and 3 #MyCalculator"
   • "Subtract 10 from 4 #MyCalculator

Containerized Version

The previous soultion is great when you have the .NET SDK installed, and all the dependencies are in place. However, if you would like to share the solution or run it in a different environment, you can use the containerized version.

1. Start Docker and make sure it's running.
2. From a terminal, navigate in the folder 03-GettingStarted\samples\csharp\src
3. To build the Docker image for the calculator service, execute the following command (replace <YOUR-DOCKER-USERNAME> with your Docker Hub username):

   docker build -t <YOUR-DOCKER-USERNAME>/mcp-calculator .

4. After the image is built, let's upload it to Docker Hub. Run the following command:

    docker push <YOUR-DOCKER-USERNAME>/mcp-calculator

## Use the Dockerized Version

1. In the `.vscode/mcp.json` file, replace the server configuration by the following:
 ```json
  "mcp-calc": {
    "command": "docker",
    "args": [
      "run",
      "--rm",
      "-i",
      "<YOUR-DOCKER-USERNAME>/mcp-calc"
    ],
    "envFile": "",
    "env": {}
  }

Looking at the configuration, you can see that the command is docker and the args are run --rm -i <YOUR-DOCKER-USERNAME>/mcp-calc. The --rm flag ensures that the container is removed after it stops, and the -i flag allows you to interact with the container's standard input. The last argument is the name of the image we just built and pushed to Docker Hub.

Test the Dockerized Version

Start the MCP Server by clicking the little Start button above "mcp-calc": {, and just like before you can ask the calculator service to do some math for you.