MCPFileServer by undici77 - MCP Server

📂 MCP File Server

MCP File Server is a secure, sandboxed file server providing controlled access to filesystem operations via the Model Control Protocol (MCP). It supports reading, writing, listing, creating, and deleting files and directories within a configurable working directory while enforcing strict security checks.

Features
Installation & Quick Start
Command‑Line Options
Integration with LM Studio
MCP API Overview
Available Tools
Security Features

🎯 Features

Sandboxed operations – all paths are confined to a user‑specified working directory.
Path traversal protection, file‑size limits, and blocked extensions.
Binary support via Base64 encoding for safe transport of non‑text data.
Simple line‑delimited JSON‑RPC protocol suitable for stdin/stdout integration.
Ready‑to‑use with LM Studio through a minimal mcp.json configuration.

📦 Installation & Quick Start

# Clone the repository (if not already done)
git clone https://github.com/undici77/MCPFileServer.git
cd MCPFileServer

# Run the startup script – it creates a virtual environment,
# installs dependencies, and starts the server.
./run.sh -d /path/to/working/directory

The script will:

Verify that Python 3 is available.
Create a .venv virtual environment (if missing).
Install required packages (aiofiles).
Start main.py with the supplied working directory.

📌 Tip: Ensure the script has execution permission:
chmod +x run.sh

⚙️ Command‑Line Options

Option	Description
`-d`, `--directory`	Path to the working directory. If omitted, the server uses the current process directory. The directory must exist and be readable/writable.

🤝 Integration with LM Studio

Add an entry for the file server in your project's mcp.json:

{
  "mcpServers": {
    "file-server": {
      "command": "/absolute/path/to/MCPFileServer/run.sh",
      "args": [
        "-d",
        "/absolute/path/to/working/directory"
      ],
      "env": {
        "WORKING_DIR": "."
      }
    }
  }
}

Replace the paths with absolute locations on your machine.
Ensure run.sh is executable (chmod +x run.sh) and dependencies are installed.

📡 MCP API Overview

All communication follows JSON‑RPC 2.0 over stdin/stdout.

`initialize`

Sent by the client to obtain server capabilities.

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "initialize",
  "params": {}
}

The server responds with protocol version, capabilities, and its name/version.

`tools/list`

Retrieves a machine‑readable list of supported tools.

{
  "jsonrpc": "2.0",
  "id": 2,
  "method": "tools/list",
  "params": {}
}

The response contains an array of tool definitions (name, description, input schema).

`tools/call`

Invokes a specific tool.

{
  "jsonrpc": "2.0",
  "id": 3,
  "method": "tools/call",
  "params": {
    "name": "<tool_name>",
    "arguments": { … }
  }
}

Note: The key for the tool name is **name**, not tool. This matches the server implementation.

🛠️ Available Tools

Tool	Description
`read_file`	Read a file’s contents (text or binary).
`write_file`	Write text or Base64‑encoded binary data to a file.
`list_files`	List files and directories with optional filtering.
`create_directory`	Create a new sub‑directory (parents created as needed).
`delete_file`	Delete a single file.
`delete_directory`	Remove a directory; optionally force deletion of non‑empty trees.
`search_in_file`	Search for a string in a file or recursively in a directory, returning contextual excerpts.

read_file

Read the contents of a file inside the working directory. Parameters

Name	Type	Required	Description
`path`	string	✅	Relative path to the target file.
`binary`	boolean	❌ (default: `false`)	Set to `true` to read the file as binary; the result is Base64‑encoded.
Example

{
  "method": "tools/call",
  "params": {
    "name": "read_file",
    "arguments": {
      "path": "example.txt",
      "binary": false
    }
  }
}

write_file

Write content to a file (creating intermediate directories if needed). Parameters

Name	Type	Required	Description
`path`	string	✅	Relative path of the target file.
`content`	string	✅	Text to write, or Base64‑encoded binary data when `binary=true`.
`binary`	boolean	❌ (default: `false`)	Set to `true` to treat `content` as Base64‑encoded binary.
Example

{
  "method": "tools/call",
  "params": {
    "name": "write_file",
    "arguments": {
      "path": "output.txt",
      "content": "Hello, world!",
      "binary": false
    }
  }
}

list_files

List files and directories under the working directory. Parameters

Name	Type	Required	Description
`extensions`	array of strings	❌	Filter by file extensions (e.g., `[".py", ".txt"]`). If omitted, all files are listed.
`recursive`	boolean	❌ (default: `true`)	Search sub‑directories recursively when `true`.
`show_empty_dirs`	boolean	❌ (default: `true`)	Include directories that contain no matching files.
Example

{
  "method": "tools/call",
  "params": {
    "name": "list_files",
    "arguments": {
      "extensions": [".py", ".txt"],
      "recursive": true,
      "show_empty_dirs": false
    }
  }
}

The response lists entries prefixed with DIR: or FILE: and includes a summary line.

create_directory

Create a new directory (including any missing parent directories). Parameters

Name	Type	Required	Description
`path`	string	✅	Relative path of the directory to create.
Example

{
  "method": "tools/call",
  "params": {
    "name": "create_directory",
    "arguments": { "path": "new_folder/subfolder" }
  }
}

delete_file

Delete a file inside the working directory. Parameters

Name	Type	Required	Description
`path`	string	✅	Relative path of the file to delete.
Example

{
  "method": "tools/call",
  "params": {
    "name": "delete_file",
    "arguments": { "path": "temp.txt" }
  }
}

delete_directory

Delete a directory, optionally forcing removal of its contents. Parameters

Name	Type	Required	Description
`path`	string	✅	Relative path of the directory to delete.
`force`	boolean	❌ (default: `false`)	When `true`, deletes non‑empty directories recursively.
Example

{
  "method": "tools/call",
  "params": {
    "name": "delete_directory",
    "arguments": { "path": "old_folder", "force": true }
  }
}

search_in_file

Search for a string in a file or recursively in all files within a directory, returning contextual excerpts. Parameters

Name	Type	Required	Description
`path`	string	✅	Relative path to a file or directory.
`search_string`	string	✅	Text to search for.
`context_lines`	integer	❌ (default: `3`)	Number of lines before and after each match to include.
`case_sensitive`	boolean	❌ (default: `false`)	Perform a case‑sensitive search when `true`.
`max_matches`	integer	❌ (default: `50`)	Maximum matches returned per file.
Example

{
  "method": "tools/call",
  "params": {
    "name": "search_in_file",
    "arguments": {
      "path": "log.txt",
      "search_string": "ERROR",
      "context_lines": 2,
      "case_sensitive": false,
      "max_matches": 10
    }
  }
}

The response contains formatted excerpts with line numbers and a summary of total matches.

🔐 Security Features

Path traversal protection – all paths are resolved against the working directory; attempts to escape result in an error.
Blocked extensions & sensitive filenames – files such as .exe, .bat, passwd, etc., are rejected.
File‑size limits – reads/writes exceeding 100 MiB (MAX_FILE_SIZE) are denied.
Null byte and dangerous pattern checks – prevent malformed input attacks.