MCP Diagnostics Service

A VS Code extension that exposes diagnostics (Problems panel) as an MCP service for LLM integration.

Features

• MCP Server: Start a local MCP server that LLMs can connect to
• Get Diagnostics: Retrieve all current errors, warnings, and hints from VS Code
• Get File Context: Read source files for code context
• Built-in Fix Prompt: Pre-configured prompt for diagnostics-driven code fixing
• Sidebar View: Visual status and control panel for MCP service
• HTTP SSE Transport: Uses HTTP Server-Sent Events for reliable communication

Installation

Install from VS Code Marketplace

Search for "MCP Diagnostics Service" in VS Code Extensions view and install.

Install from VSIX Package

# Build the VSIX package
npm run package:vsix

# Install the package
code --install-extension mcp-diagnostics-*.vsix

Usage

Start the MCP Service

1. Open VS Code
2. Open the MCP Diagnostics sidebar panel from the Activity Bar
3. Click the Enable MCP Diagnostics Service button (or run Ctrl+Shift+P → Enable MCP Diagnostics Service)

Get MCP Configuration

1. Open Command Palette (Ctrl+Shift+P)
2. Run Show MCP Configuration
3. Copy the displayed JSON configuration

Configure Your LLM Client

Paste the configuration into your LLM client's MCP settings:

Claude Desktop (claude_desktop_config.json):

{
  "mcpServers": {
    "mcp-diagnostics": {
      "transport": {
        "type": "sse",
        "url": "http://localhost:YOUR_PORT"
      }
    }
  }
}

Note: Replace YOUR_PORT with the actual port number shown in the sidebar panel.

MCP Configuration

Use the "Show MCP Configuration" command to obtain a ready-to-use MCP configuration JSON.

This MCP service is:

• Diagnostics-only: Only provides read access to VS Code diagnostics
• Read-only: Cannot modify your code
• Secure: Runs locally on your machine with configurable port

Available Tools

get_diagnostics

Get all current diagnostics (errors, warnings, hints) from the active VS Code workspace.

Response: JSON array of all diagnostic items with file paths, line numbers, severity, and messages.

get_file_context

Retrieve the full content of a source file from the current VS Code workspace.

Parameters:

• path (string): The file path to read

Response: Full file contents with line numbers for context.

get_fix_prompt

Get the built-in diagnostics fixing prompt optimized for LLM code assistance.

Response: A structured prompt template for diagnostics-driven code fixing.

Configuration

You can configure the extension in VS Code Settings:

• Port: HTTP server port for MCP SSE connection (default: 0 for random port)
  • Setting: mcpDiagnostics.port
  • Range: 0-65535 (0 = automatically assign available port)

Development

# Install dependencies
npm install

# Compile TypeScript
npm run compile

# Watch mode (auto-recompile on changes)
npm run watch

# Package for production (minified)
npm run package

# Create VSIX package
npm run package:vsix

# Package and publish to marketplace
npm run publish

# Lint code
npm run lint

Project Structure

mcp-diagnostics/
├── src/
│   ├── extension.ts       # VS Code extension entry point
│   └── mcp/
│       ├── server.ts      # MCP server implementation
│       └── config.ts      # MCP configuration utilities
├── resources/
│   └── sidebar.svg        # Sidebar icon
├── esbuild.js             # Build configuration
├── tsconfig.json          # TypeScript configuration
└── package.json           # Extension manifest

Building

This project uses esbuild for fast TypeScript compilation:

• npm run compile → Build out/extension.js with source maps
• npm run package → Production build with minification
• npm run watch → Watch mode for development

The extension is bundled into a single CommonJS module with vscode module externalized.

Security

• All diagnostics are read from VS Code's internal API
• No code execution or modification capabilities
• File reading is limited to workspace files
• Server runs locally and does not expose to external network

License

MIT

Repository

https://github.com/Fromsko-work/mcp-diagnostics

Contributing

Contributions are welcome! Please feel free to submit issues and pull requests.