FileSystem MCP Server

FileSystem MCP Server

Local MCP server for Visual Studio 2022+ that provides code-workspace functionality by giving AI agents selective access to project folders and files

Table of Contents

• [🎯 Target Environment](#-target-environment)
• [Features](#features)
• [Installation](#installation)
• [Quick Start](#quick-start)
• [Configuration Options](#configuration-options)
• [Option 1: Config.json File (Simplest - Recommended for Beginners)](#option-1-configjson-file-simplest---recommended-for-beginners)
• [Option 2: Command-Line Arguments (Advanced - For MCP Clients)](#option-2-command-line-arguments-advanced---for-mcp-clients)
• [Option 3: Hybrid Approach (Best of Both Worlds)](#option-3-hybrid-approach-best-of-both-worlds)
• [Usage](#usage)
• [Command Line Examples](#command-line-examples)
• [Available Tools](#available-tools)
• [Why This Hybrid Approach is Perfect](#why-this-hybrid-approach-is-perfect)
• [Visual Studio 2022+ Debugging](#visual-studio-2022-debugging)
• [Visual Studio 2022+ Usage Examples](#visual-studio-2022-usage-examples)
• [Editing Your mcp.json File via GitHub Copilot Chat](#editing-your-mcpjson-file-via-github-copilot-chat)
• [Security](#security)
• [Error Handling](#error-handling)
• [Troubleshooting](#troubleshooting)
• [MCP Configuration Issues](#mcp-configuration-issues)
• [Visual Studio 2022+ Debugging](#visual-studio-2022-debugging-1)
• [Common Issues](#common-issues)
• [Command Line Reference](#command-line-reference)
• [Cross-Platform Path Support](#cross-platform-path-support)
• [Advanced & Real-World MCP Configuration Examples](#advanced--real-world-mcp-configuration-examples)

---

🎯 Target Environment

This MCP server is optimized for:

• Visual Studio 2022+ development workflows
• Local development environments without complex workspace setups
• Direct folder access scenarios where you need filesystem operations
• Development environments that don't use .code-workspace files
• Individual project directories rather than multi-root workspaces

Features

• Directory Traversal: List contents of allowed directories
• File Reading: Read contents of files with allowed extensions
• File Writing: Write text/binary content to files — opt-in via --allow-write (disabled by default)
• Directory Validation: Check accessibility of configured directories
• Hybrid Configuration: Command-line arguments (MCP) + config.json fallback (debugging)
• Visual Studio 2022+ Debugging: No-argument startup support
• Cross-Platform Path Support: Automatically handles both Windows (\) and Unix (/) path separators
• Security: Access restricted to explicitly specified directories and file types
• Local Development Focus: Perfect for Visual Studio 2022+ and similar environments

Installation

From PyPI (Recommended for Users)

pip install vs-filesystem-mcp-server

From Source (For Development)

1. Ensure you have Python 3.10+ installed
2. Clone the repository
3. Navigate to the project directory
4. Install dependencies using uv:

``bash uv sync ``

Quick Start

1. For MCP usage: Add the corrected configuration to your .mcp.json
2. For debugging: Just press F5 in Visual Studio 2022+ - uses config.json automatically
3. Test your configuration by calling the init() tool first
4. If init() returns errors, check your directory paths and permissions

Configuration Options

Option 1: Config.json File (Simplest - Recommended for Beginners)

The easiest way to get started! Create a config.json file:

For MCP server usage:

• Place config.json in the same folder as your .mcp.json file (usually C:\Users\YourUsername\)

For debugging from source (Visual Studio 2022+):

• Place config.json in the same directory as app.py (D:/Projects/filesystem_server/)

{
  "allowed_dirs": [
    "C:/Users/YourUsername/Documents/projects",
    "D:/projects",
    "D:/Webs"
  ],
  "allowed_extensions": [
    ".py", ".js", ".ts", ".json", ".md", ".txt",
    ".yml", ".yaml", ".toml", ".cfg", ".ini", ".cs",
    ".css", ".scss", ".htm", ".html", ".xml", ".xaml"
  ],
  "allow_write": false
}

> Note: Set "allow_write": true to enable write_file and write_file_binary tools.

MCP Configuration (Installed via pip)

Add this to your .mcp.json file (usually C:\Users\YourUsername\ in VS 2022+):

{
  "servers": {
    "filesystem-server": {
      "command": "vs-filesystem-mcp-server"
    }
  }
}

Note: When installed via pip, the command is just vs-filesystem-mcp-server - no path to app.py needed!

MCP Configuration (Running from Source)

If you're developing and running from source code:

{
  "servers": {
    "filesystem-server": {
      "command": "python",
      "args": [
        "/absolute/path/to/your/project/filesystem_server/app.py"
      ],
      "cwd": "/absolute/path/to/your/project/filesystem_server"
    }
  }
}

Benefits:

• ✅ No command-line arguments needed
• ✅ Perfect for Visual Studio 2022 debugging (just press F5)
• ✅ Works with MCP clients when placed in correct location
• ✅ Easy to edit and modify
• ✅ Great for testing and development

Usage:

# For debugging in Visual Studio 2022:
python app.py  # Uses config.json from same directory as app.py

# For MCP server usage:
# The MCP client automatically finds config.json in the .mcp.json directory

Important Location Notes:

• 🔧 Debugging: config.json goes next to app.py
• 🌐 MCP Server: config.json goes next to .mcp.json
• 📁 Different locations for different use cases!

Option 2: Command-Line Arguments (Advanced - For MCP Clients)

Best for production MCP client configurations where you want everything in one place:

When Installed via pip

{
  "servers": {
    "filesystem-server": {
      "command": "vs-filesystem-mcp-server",
      "args": [
        "--allowed-dirs", "D:/projects", "D:/Webs",
        "--allowed-extensions", ".py", ".js", ".ts", ".json", ".md", ".txt"
      ]
    }
  }
}

When Running from Source

python app.py --allowed-dirs "D:/projects" "D:/Webs" --allowed-extensions ".py" ".js" ".md"

# With write access enabled:
python app.py --allowed-dirs "D:/projects" "D:/Webs" --allowed-extensions ".py" ".js" ".md" --allow-write true

MCP Client Configuration (.mcp.json):

{
  "servers": {
    "filesystem-server": {
      "command": "python",
      "args": [
        "/absolute/path/to/your/project/filesystem_server/app.py",
        "--allowed-dirs", "D:/projects", "D:/Webs",
        "--allowed-extensions", ".py", ".js", ".ts", ".json", ".md", ".txt"
      ],
      "cwd": "/absolute/path/to/your/project/filesystem_server"
    }
  }
}

Benefits:

• ✅ Self-contained configuration
• ✅ No external config files needed
• ✅ Version control friendly
• ✅ Explicit and visible in MCP setup

Option 3: Hybrid Approach (Best of Both Worlds)

The server automatically uses command-line arguments first, then falls back to config.json if no arguments provided.

How it works:

• MCP clients: Use command-line arguments (Option 2)
• Visual Studio debugging: Automatically uses config.json (Option 1)
• Priority: Command-line args override config.json when present

Benefits:

• ✅ Works for both MCP clients and debugging
• ✅ No conflicts between different usage scenarios
• ✅ Flexible and developer-friendly
• ✅ Choose the best option for each situation

Usage

Command Line Examples

# With command line arguments (MCP clients):
python app.py --allowed-dirs "D:/projects" "D:/Webs" --allowed-extensions ".py" ".js" ".md"

# Using config.json fallback (Visual Studio 2022+ debugging):
python app.py

# Show MCP configuration help:
python app.py --help-mcp

Available Tools

1. init(directory, file_path) - Validates accessibility of configured directories and can optionally list a directory and/or read a file

• directory (optional): Directory path to list contents (can be None)
• file_path (optional): File path to read content (can be None)
• Returns { "message": "OK", "isError": false, ... } if all directories accessible
• Returns error details if any directories are inaccessible
• Shows configuration source (command-line args vs config file)
• Use this to verify your configuration before using other tools

1. list_directory(directory, report_progress=True, batch_size=100) - Lists files and subdirectories in a given directory, with optional progress reporting

• directory: The absolute or relative path to the directory (supports both / and \\ separators)
• report_progress (optional): If True, returns progress information and batch details (default: True)
• batch_size (optional): Number of items to process before reporting progress (default: 100)
• Returns a list of file and directory names if report_progress is False
• Returns a dictionary with contents, progressinfo, totalitems, and processing_time if report_progress is True
• If an error occurs, returns a dictionary with "error" and "error_message" keys
• No exceptions are raised - all errors are returned as part of the result

1. read_file(file_path) - Reads the content of a specified file as text

• Returns the file content as a string (for text files only)
• Not suitable for binary files (images, audio, etc.)

1. read_file_binary(file_path) - Reads the content of a specified file as base64-encoded binary

• Returns { "content_base64": , "encoding": "base64", "error": False } on success
• Returns an error dict if the file is not allowed or not found
• Suitable for images, audio, and other binary files

1. list_resources(directory=None, report_progress=True, batch_size=100) - Lists all resources (files and directories) in a directory (or all allowed directories) in MCP resource format

• directory (optional): Directory to start from (defaults to all allowed_dirs)
• report_progress (optional): If True, returns progress information and batches (default: True)
• batch_size (optional): Number of resources per progress batch (default: 100)
• Returns a list of resource objects if report_progress is False
• Returns a dictionary with contents, progressinfo, totalitems, and processing_time if report_progress is True
• Example resource object:

``json { "id": "D:/projects/example.txt", "type": "file", "name": "example.txt", "path": "D:/projects/example.txt", "metadata": { "size": 1234, "modified": "2025-08-18T12:34:56Z" }, "actions": ["read", "read_binary", "write", "write_binary"] } ``

1. get_resource(path) - Gets metadata and actions for a specific file or directory

• path: Absolute or relative path to the resource
• Returns a resource object (id, type, name, path, metadata, actions) or an error dict
• For files, includes size and modified time; for directories, includes type and actions
• Does not return file content

1. write_file(file_path, content) - Writes text content to a specified file (requires --allow-write)

• file_path: Path to write to (must be within allowed dirs)
• content: Text string to write
• Raises ValueError if write access is disabled, path not allowed, extension not allowed, or IO error
• Overwrites existing file
• Disabled by default — enable with --allow-write flag or "allow_write": true in config.json

1. write_file_binary(file_path, content_base64) - Writes binary content from base64 to file (requires --allow-write)

• file_path: Path to write to (must be within allowed dirs)
• content_base64: Base64-encoded binary data
• Returns {"success": true, "bytes_written": int, "error": false} or error dict
• Overwrites existing file, suitable for images/binaries
• Disabled by default — enable with --allow-write flag or "allow_write": true in config.json

Why This Hybrid Approach is Perfect

• ✅ MCP clients: Use efficient command-line arguments
• ✅ Visual Studio 2022: Zero-friction debugging with config.json fallback
• ✅ No conflicts: Priority system handles both scenarios gracefully
• ✅ Developer-friendly: Works however you want to run it
• ✅ Best of both worlds: MCP efficiency + debugging convenience

Visual Studio 2022+ Debugging

Perfect debugging experience:

• ✅ No command-line arguments needed
• ✅ Just press F5 to start debugging
• ✅ Automatically uses config.json
• ✅ Set breakpoints and debug normally
• ✅ Full IntelliSense and debugging support

Debugging setup:

1. Open the project in Visual Studio 2022
2. Ensure config.json exists (already created for you)
3. Press F5 or Debug > Start Debugging
4. Server starts with your configured directories

Visual Studio 2022+ Usage Examples

Below are step-by-step examples showing how to call the FileSystem MCP Server from within Visual Studio 2022. These screenshots demonstrate the process using the alias "fss" for the server, which is simply a shorter name for "filesystem-server". You can customize this alias in your .mcp.json file—the actual name is up to you.

> Note: All images are located in the images/ subfolder.

Step 1: Calling the Server Tool

In this example, the MCP client is configured to use "fss" as the server name. This is just an alias for convenience.

Step 2: Viewing the Server Response

The server responds with the results of your request, such as the output from the read_file() tool.

---

> Note: > - The "fss" alias is used here for brevity. You can use any name you prefer in your .mcp.json configuration. > - To change the server name, simply update the key in your .mcp.json file from "filesystem-server" to any other name you like.

For more details on configuring your MCP client, see the [Configuration Options](#configuration-options) section above.

Editing Your mcp.json File via GitHub Copilot Chat

You can easily edit your mcp.json configuration file directly from Visual Studio using the GitHub Copilot Chat interface. Follow these steps:

1. Click the Tools icon on the right side of Visual Studio, while in Agent mode.
2. Click the arrow next to any MCP server in the list.
3. Choose Edit – the mcp.json file will open for editing.

This allows you to quickly update your MCP server configuration without leaving the IDE.

Security

• Only directories specified in --allowed-dirs or config.json can be accessed
• Only files with extensions in --allowed-extensions or config.json can be read or written
• Write access disabled by default: write_file and write_file_binary require --allow-write flag or "allow_write": true in config.json
• All paths are validated before access
• The server runs with the permissions of the user account
• Perfect for local development: Secure access to your project directories

Error Handling

The server provides detailed error messages for:

• Unauthorized directory access
• Invalid file paths
• Unsupported file extensions
• Missing configuration (shows helpful guidance for both MCP and debugging scenarios)
• Directory accessibility issues (via init() tool)

New Error Handling for list_directory():

• The list_directory() function now returns errors as part of the result list instead of raising exceptions
• Error format: ["error", "detailed_error_message"]
• This makes it easier for MCP clients to handle errors gracefully without exception handling
• Successful calls return the normal list of directory contents

Troubleshooting

MCP Configuration Issues

Your original config had a missing comma after "D:/Webs". The corrected version above fixes

…

Source & license

This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: Oncorporation
• Source: Oncorporation/filesystem_server
• License: Apache-2.0

Install and usage instructions live in the source repository linked above.