OpenCliToMcp Framework

A comprehensive framework for automatically generating Model Context Protocol (MCP) servers from OpenCLI specifications, enabling seamless integration of command-line tools with MCP-compatible clients.

🚀 Overview

OpenCliToMcp.Generator is a .NET Standard 2.0 Source Generator that transforms OpenCLI-compliant command-line applications into MCP servers, using the ModelContextProtocol C# SDK, allowing them to be used as tools within LLM conversations.

📁 Repository Structure

OpenCliToMcp/
├── Solutions/
│   ├── OpenCliToMcp.Core/              # Core framework components
│   ├── OpenCliToMcp.Generator/         # Source generator for MCP servers
│   ├── TaskManager.Cli/                # Demo CLI application
│   ├── TaskManager.McpServer/          # MCP server (STDIO transport)
│   ├── Weather.Cli/                    # Demo CLI application
│   ├── Weather.McpServer/              # MCP server (HTTP transport)
│   └── *.Tests/                        # Comprehensive test suites
├── knowledge-base/                     # Documentation and specifications
└── README.md                           # This file

Core Components

• OpenCliToMcp.Core: Foundation classes for CLI execution and MCP integration
• OpenCliToMcp.Generator: Source generator that creates MCP server implementations
• Demo Applications: TaskManager and Weather CLIs with full OpenCLI specifications
• MCP Servers: Generated servers demonstrating both transport types

🛠️ Getting Started

Prerequisites

• .NET 9.0 SDK or later
• .NET Compiler Platform SDK (required for source generator development)
• Visual Studio 2022 or VS Code with C# Dev Kit
• Claude Desktop or VS Code with MCP extension

Setup

Before building the solution, ensure your development environment is properly configured:

1. Install .NET Compiler Platform SDK (required for source generator development):

   This component must be installed via the Visual Studio Installer.

   • Open Visual Studio Installer.
   • Click Modify on your Visual Studio installation.
   • Go to the Individual components tab.
   • Search for .NET Compiler Platform SDK and check the box.
   • Click Modify to install.

2. Update .NET workloads (for other components):

   dotnet workload update
   

3. Restore NuGet packages:

   dotnet restore
   

4. Verify SDK installation:

   dotnet --version
   

Building the Project

cd Solutions
dotnet build

Running the Demo Servers

TaskManager MCP Server (STDIO)

cd TaskManager.McpServer
dotnet run

Weather MCP Server (HTTP)

cd Weather.McpServer
dotnet run

🔧 MCP Client Configuration

VS Code Configuration

Create or update your MCP configuration file for use in VS Code:

Windows: %APPDATA%\Code\User\mcp.json macOS: ~/Library/Application Support/Code/User/mcp.json Linux: ~/.config/Code/User/mcp.json

{
    "servers": {
        "weather-cli-app": {
            "url": "http://localhost:5000/",
            "type": "http"
        },
        "task-manager-cli-app": {
            "type": "stdio",
            "command": "C:\\path\\to\\Solutions\\TaskManager.McpServer\\bin\\Debug\\net9.0\\TaskManager.McpServer.exe",
            "args": []
        }
    },
    "inputs": []
}

Cross-Platform Path Configuration

Windows

{
    "command": "C:\\path\\to\\project\\TaskManager.McpServer\\bin\\Debug\\net9.0\\TaskManager.McpServer.exe"
}

macOS/Linux

{
    "command": "/path/to/project/TaskManager.McpServer/bin/Debug/net9.0/TaskManager.McpServer"
}

🎯 Available Tools

TaskManager Tools

• Task Management: Create, update, delete, and show tasks
• Project Management: Create, list, and archive projects
• Statistics: View task statistics with filtering options
• Export: Export tasks to JSON, CSV, or Markdown formats
• List & Filter: Advanced filtering by status, priority, assignee, project

Example Usage

Create a high-priority task called "Review pull request" assigned to john

Weather Tools

• Current Weather: Get current weather conditions for any city
• Forecast: Multi-day weather forecasts with customizable periods
• Compare: Compare weather between multiple cities
• Location Management: Save and manage favorite locations
• Unit Conversion: Support for Celsius, Fahrenheit, and Kelvin

Example Usage

What's the weather like in London compared to Paris?

🔨 Using the Source Generator

The OpenCliToMcp.Generator provides two approaches for generating MCP servers from OpenCLI specifications:

Approach 1: OpenCliTool Attribute

Use the [OpenCliTool] attribute to generate MCP tool methods in a partial class:

using OpenCliToMcp;
using OpenCliToMcp.Core;

namespace Weather.McpServer;

[OpenCliTool("../Weather.Cli/weather-opencli.json")]
public partial class WeatherCliMcpTool
{
    private readonly ICliExecutor cliExecutor;
    
    public WeatherCliMcpTool(ICliExecutor cliExecutor)
    {
        ArgumentNullException.ThrowIfNull(cliExecutor);
        this.cliExecutor = cliExecutor;
    }
}

This approach:

• Creates a partial class with generated MCP tool methods
• Uses dependency injection for the ICliExecutor
• Ideal for custom implementations and testing

Approach 2: AdditionalFiles ItemGroup

Add the OpenCLI specification as an AdditionalFiles item in your project file:

<ItemGroup>
    <AdditionalFiles Include="..\TaskManager.Cli\taskmanager.opencli.json" 
                     Link="taskmanager.opencli.json" />
</ItemGroup>

This approach:

• Automatically generates the complete MCP server implementation
• No manual coding required
• Ideal for quick MCP server creation from existing CLIs

Project Configuration

Both approaches require adding the source generator to your project:

<ItemGroup>
    <ProjectReference Include="..\OpenCliToMcp.Generator\OpenCliToMcp.Generator.csproj" 
                      OutputItemType="Analyzer" 
                      ReferenceOutputAssembly="false" />
    <ProjectReference Include="..\OpenCliToMcp.Core\OpenCliToMcp.Core.csproj" />
</ItemGroup>

🏗️ Architecture

Code Generation Process

1. OpenCLI Specification: Define CLI commands in *.opencli.json
2. Source Generator: Automatically generates MCP server implementations
3. Runtime Integration: Seamless integration with MCP clients

Transport Types

HTTP Transport (Weather.McpServer)

• Runs as web service on localhost:5000
• Suitable for development and local testing
• Automatic service discovery

STDIO Transport (TaskManager.McpServer)

• Direct process communication
• Lower overhead for frequent operations
• Ideal for production deployments

📝 CLI Specifications

TaskManager Commands

The TaskManager CLI supports comprehensive task and project management:

• Tasks: add, update, delete, show, list
• Projects: create, list, archive
• Statistics: Detailed reporting with filtering
• Export: Multiple format support (JSON, CSV, Markdown)

Weather Commands

The Weather CLI provides comprehensive weather information:

• Current: Real-time weather data
• Forecast: Multi-day predictions (1-14 days)
• Compare: Side-by-side city comparisons
• Locations: Favorite location management

📄 License

This project is licensed under the APACHE License - see the LICENSE file for details.

🙏 Acknowledgments

• Model Context Protocol specification
• OpenCLI specification contributors

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Built entirely from prompts with Claude Code using Opus 4 & Sonnet 4 models