VSC-MCP

VSC-MCP

This project provides tools that expose Language Server Protocol (LSP) functionality as MCP (Model Context Protocol) tools. It enables AI clients to programmatically analyze and edit code through standardized MCP tool calls.

It started as a simple project focused on coding only with TypeScript, then evolved to a full-featured MCP server that supports any language supported by VS Code.

Full details about latest changes and migration to headless VC Code can be found here

Docker Mode & VS Code LSP Integration

VSC-MCP can run in two modes:

• Standalone Mode: It spawn a local typescript-language-server to provide LSP support ONLY for TypeScript/JavaScript.
• Docker Mode: Leverages a headless VS Code port by Gitpod, namely OpenVSCode Server, running in Docker to provide richer LSP support, for any languages supported by VC Code like Rust, Go, C#, Python, etc.

Why Docker Mode?

• Unified LSP: Avoids the hassle of launching separate local language servers for each language.
• Rich Extension Ecosystem: Inherits VS Code's extension support and APIs for advanced language features.
• Live Editing: Open http://localhost:3000 to watch edits in real time as your AI agent interacts with MCP.
• Works without IDE: we can write and analyze code without opening any IDE.

How It Works

1. OpenVSCode Server runs inside Docker, exposing port 3000 (IDE UI) and 5007 (LSP bridge).
2. Required VS Code extensions are pre-installed (e.g., rust-analyzer, pyright, eslint, and the VSC-MCP extension).
3. The VSC-MCP extension creates a WebSocket channel between MCP and the VS Code back-end.
4. File I/O tools use direct access; LSP tools use VS Code's internal language servers.

Installation

Prerequisites

• Docker (for running the VS Code server)
• Bun (for launching MCP)

Setup

1. Clone the repository and cd into it.
2. Install dependencies

   bun install
   

3. Build and start OpenVSCode Server (mount your project into the container)

   PROJECT_PATH=/path/to/your/project docker-compose up
   

4. Register MCP in your AI client (example settings.json)

   {
     "mcpServers": {
       "vsc-mcp": {
         "command": "bun",
         "args": ["<vsc_mcp_cloned_dir>/src/index.ts"],
         "env": {
           "USE_VSCODE_LSP": "true",
           "LOG_DIR": "<vsc_mcp_cloned_dir>/logs",
           "ALLOWED_DIRECTORIES": "/path/to/your/project"
         }
       }
     }
   }
   

Environment Variables

Variable	Purpose
USE_VSCODE_LSP	Set to true to enable Docker/VS Code LSP mode. MCP will forward LSP requests to VS Code (port 5007) instead of spawning a local language server.
ALLOWED_DIRECTORIES	Restricts direct-file manipulation to the specified directories.
LOG_DIR	Where MCP writes logs for debugging.

Note: By default, USE_VSCODE_LSP is false (standalone mode). Set it to true to use Docker/VS Code LSP integration.

Suggested AI Client Configurations

Claude Desktop

For now the best workflow is to use Claude Desktop as AI Client, it support MCP servers and it provide a monthly plan for 20$/month, and by using the VSC-MCP tools, we can "chat" and work with our codebase.

• On MacOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• On Windows: %APPDATA%/Claude/claude_desktop_config.json

Add the following configurations to the mcp_servers section of the config file:

{
  "mcpServers": {
    "repomix": {
      "command": "npx",
      "args": [
        "-y",
        "repomix",
        "--mcp"
      ]
    },
    "vsc-mcp": {
      "command": "bun",
      "args": [
        "<vsc_mcp_cloned_dir>/src/index.ts"
      ],
      "env": {
        "USE_VSCODE_LSP": "true",
        "LOG_DIR": "<vsc_mcp_cloned_dir>/logs",
        "ALLOWED_DIRECTORIES": "/path/to/your/project"
      }
    }
  }
}

We suggest to add the repomix mcp server dependency, to know why, you can read this blog post.

Replace <vsc_mcp_cloned_dir> with the actual path to your vsc-mcp cloned directory.

Security Features

Docker Workspace Restriction

When we start docker we need to specify the workspace directory.

PROJECT_PATH=/path/to/your/project docker-compose up

VSC-MCP tools will only be able to access files in the workspace directory.

Path Restriction

The VSC-MCP tools include a security feature to restrict OS file operations (read and write files on disk) to specific directories:

• ALLOWED_DIRECTORIES: An environment variable that specifies a comma-separated list of directories where file operations are permitted.

  Example:

  ALLOWED_DIRECTORIES=/home/user/projects,/tmp/workspace
  

• If this environment variable is not set, operations default to the current working directory only.

• All file operations (read, write, edit) will check if the target path is within the allowed directories.

• Attempting to access files outside allowed directories will result in an "Access denied" error.

This feature helps prevent unauthorized access to sensitive files and directories on the system.

Available Tools

Currently, the following tools are available:

• edit_symbol: Edits a symbol (function, class, method, etc.) by name and type in a given file using LSP.

  • Supports various symbol types: function, method, class, interface, variable, constant, property, field
  • Uses LSP's workspace/symbol and textDocument/documentSymbol requests to find symbols
  • Applies edits directly to files

• read_symbol: Reads a symbol (function, class, method, etc.) by name and type in a given file using LSP.

  • Supports the same symbol types as editSymbol
  • Uses LSP to locate the symbol and extract its content
  • Returns the symbol content along with its location information

• read_file: Reads the content of a file.

  • Returns the file content with appropriate MIME type based on file extension
  • Handles various file formats including code, text, and configuration files
  • Provides detailed error messages for common issues (file not found, directory access, etc.)

• write_file: Creates a new file or overwrites an existing file with the provided content.

  • Creates parent directories if they don't exist
  • Supports any file type
  • Returns information about the file operation (created/overwritten, file size)

• search_replace_file: Searches for content in a file and replaces it with new content.

  • Ignores whitespace differences when searching (spaces, tabs, newlines)
  • Supports flexible matching of content patterns
  • Returns the number of replacements made

• get_errors: Fetches code errors and issues for a specific file using the LSP textDocument/diagnostic API.

  • Provides detailed diagnostics including error messages, severity, and location
  • Uses the VS Code extension's diagnostics api to validate code
  • Returns structured information about code issues

• find_references: Finds all references to a symbol (function, class, etc.) by name and type in a given file using LSP.

  • Supports various symbol types: function, method, class, interface, variable, constant, property, field
  • Uses LSP's textDocument/reference API to find all references to a symbol
  • Returns a list of references with file paths and positions
  • Helps with code analysis, refactoring, and understanding code usage