csharp-lsp-mcp

An MCP (Model Context Protocol) server that provides C# and XAML language intelligence for AI assistants like Claude. It bridges the gap between LLMs and .NET development by exposing IntelliSense, diagnostics, and code analysis through the standardized MCP protocol.

Features

C# Language Intelligence (via csharp-ls)

• Diagnostics - Get compiler errors and warnings in real-time
• Hover Information - View type information and documentation
• IntelliSense Completions - Get context-aware code suggestions
• Go to Definition - Navigate to symbol definitions
• Find References - Locate all usages of a symbol
• Document Symbols - List all symbols in a file
• Code Actions - Access quick fixes and refactorings
• Rename Preview - Preview symbol renames across the workspace
• Stop/Restart - Stop the LSP server to release file locks before rebuilding

XAML Analysis (built-in)

• Validation - Check XAML for errors and issues
• Binding Analysis - Extract and analyze data bindings
• Resource Inspection - List and verify resource references
• Name Discovery - Find all x:Name declarations
• Structure Visualization - View element tree hierarchy
• Binding Error Detection - Identify binding problems
• ViewModel Generation - Generate ViewModels from bindings

Prerequisites

1. .NET 8.0 SDK or later
2. csharp-ls - The C# Language Server

Install csharp-ls globally:

dotnet tool install --global csharp-ls

Installation

From Source

git clone https://github.com/HYMMA/csharp-lsp-mcp.git
cd csharp-lsp-mcp/csharp-lsp-mcp/src/CSharpLspMcp
dotnet build -c Release

From NuGet (coming soon)

dotnet tool install --global CSharpLspMcp

Configuration

Claude Code

Add to your ~/.claude.json:

{
  "mcpServers": {
    "csharp": {
      "command": "path/to/csharp-lsp-mcp.exe"
    }
  }
}

Or if installed as a global tool:

{
  "mcpServers": {
    "csharp": {
      "command": "csharp-lsp-mcp"
    }
  }
}

Claude Desktop

Add to your Claude Desktop configuration:

{
  "mcpServers": {
    "csharp": {
      "command": "csharp-lsp-mcp",
      "args": []
    }
  }
}

Usage

Once configured, the MCP server provides the following tools to your AI assistant:

Setting Up the Workspace

Before using C# tools, set the workspace directory:

Use csharp_set_workspace with path: "C:/path/to/your/solution"

Stopping the LSP for Rebuilds

The LSP server holds file locks on project DLLs. To rebuild your project, stop the server first:

Stop the C# LSP server so I can rebuild

After rebuilding, call csharp_set_workspace again to restart it. Switching workspaces via csharp_set_workspace automatically restarts the server.

Example Interactions

Get diagnostics for a file:

Check for errors in Program.cs

Get type information:

What type is the variable at line 15, column 10 in MyClass.cs?

Find all references:

Find all usages of the GetCustomer method

Analyze XAML bindings:

Show me all data bindings in MainWindow.xaml

Available Tools

Tool	Description
csharp_set_workspace	Set the solution/project directory (restarts LSP if workspace changes)
csharp_stop	Stop the LSP server to release file locks for rebuilding
csharp_diagnostics	Get compiler errors and warnings
csharp_hover	Get type info at a position
csharp_completions	Get IntelliSense completions
csharp_definition	Go to definition
csharp_references	Find all references
csharp_symbols	Get document symbols
csharp_code_actions	Get available code actions
csharp_rename	Preview symbol rename
xaml_validate	Validate XAML for errors
xaml_bindings	Extract data bindings
xaml_resources	List resource references
xaml_names	List x:Name declarations
xaml_structure	Show element tree
xaml_find_binding_errors	Find binding errors
xaml_extract_viewmodel	Generate ViewModel from bindings

Command Line Options

csharp-lsp-mcp [OPTIONS]

OPTIONS:
    -h, --help      Show help message
    -v, --version   Show version information
    -V, --verbose   Enable verbose logging (to stderr)

ENVIRONMENT VARIABLES:
    MCP_DEBUG=1     Enable trace-level logging

Architecture

┌─────────────────┐     MCP Protocol      ┌──────────────────┐
│  Claude / LLM   │◄────────────────────►│  csharp-lsp-mcp  │
└─────────────────┘                       └────────┬─────────┘
                                                   │
                                    ┌──────────────┴──────────────┐
                                    │                             │
                              ┌─────▼─────┐               ┌───────▼───────┐
                              │ csharp-ls │               │  XAML Parser  │
                              │   (LSP)   │               │   (built-in)  │
                              └─────┬─────┘               └───────────────┘
                                    │
                              ┌─────▼─────┐
                              │  Roslyn   │
                              │ Compiler  │
                              └───────────┘

Building from Source

# Clone the repository
git clone https://github.com/HYMMA/csharp-lsp-mcp.git
cd csharp-lsp-mcp

# Build
cd csharp-lsp-mcp/src/CSharpLspMcp
dotnet build -c Release

# Run tests (if available)
dotnet test

# Create a release build
dotnet publish -c Release -o ./publish

Contributing

We welcome contributions! Please see CONTRIBUTING.md for guidelines.

Changelog

See CHANGELOG.md for a history of changes.

License

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

Acknowledgments

• Model Context Protocol - The protocol specification
• csharp-ls - The C# Language Server
• Microsoft MCP C# SDK - The official C# SDK for MCP

Related Projects

• Claude Code - Anthropic's CLI for Claude
• MCP Servers - Official MCP server implementations