DateTime MCP Server

Model Context Protocol (MCP) Server for date/time operations - production-ready C# script for Visual Studio 2026 Copilot Chat.

🎯 Features

Provides 5 datetime tools via JSON-RPC 2.0:

• get_current_datetime - Get current date/time in any timezone
• get_iso8601_timestamp - Get UTC timestamp in ISO 8601 format
• add_days - Add or subtract days from a date
• is_weekend - Check if a date is a weekend
• get_week_number - Get ISO 8601 week number

🚀 Quick Start

1. Download

# Clone the repository
git clone https://github.com/eyjolfurgudnivatne/dotnet-mcp-datetime-server.git
cd dotnet-mcp-datetime-server

2. Configure

Create .mcp.json in your workspace root:

{
  "inputs": [],
  "servers": {
    "datetime": {
      "type": "stdio",
      "command": "dotnet",
      "args": ["DateTimeMcpServer.cs"],
      "env": {}
    }
  }
}

3. Activate in VS 2026

1. Open Copilot Chat in Visual Studio
2. Click the tool icon (⚙️ bottom of chat)
3. Expand "datetime" under "Added"
4. Check the tools you want to use
5. Start asking datetime questions!

📖 Example Usage

You: What's today's date?
Copilot: Today is Saturday, November 29, 2025 (week 48)

You: Is it weekend?
Copilot: Yes! It's Saturday, November 29, 2025

You: What day was 2 days ago?
Copilot: 2 days ago was Thursday, November 27, 2025

🔧 Requirements

• .NET 10 or later
• Visual Studio 2026 (November 2025 Feature Update or later)
• GitHub Copilot subscription

📝 Technical Highlights

• ✅ Zero warnings - IL2026/IL3050 eliminated with JSON Source Generation
• ✅ AOT-friendly - Full ahead-of-time compilation support
• ✅ No build required - Runs directly as C# script
• ✅ Production-ready - MCP-compliant with proper error handling
• ✅ Stdout-safe - No console logging pollution

🏗️ Extending

Add new tools in 4 steps:

1. Add method to DateTimeTools class
2. Add tool definition in ListTools()
3. Add case in CallTool() switch
4. Register return types in McpJsonContext

🐛 Troubleshooting

Tools not appearing?

• Restart Visual Studio
• Check .mcp.json path is relative to workspace root

"Failed" when calling tools?

• Ensure all return types registered in McpJsonContext
• Verify no console output (logging disabled)

Server shows "Cached"?

• Normal! Server starts on-demand when you call tools

📚 Resources

• Model Context Protocol
• JSON-RPC 2.0 Spec
• .NET Source Generation

🤝 Contributing

Contributions welcome! Please open an issue or PR.

📄 License

MIT License - free for any use, commercial or personal.

🎉 Acknowledgments

Built with ☕ and persistence during a Saturday research session.
Special thanks to the debugging journey that made this possible!

Author: ARKo AS - AHelse Development Team
Date: November 29, 2025
Status: Production-ready ✅