VBA MCP Server

Let AI read and write your Excel VBA code directly — no manual export/import needed.

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An MCP (Model Context Protocol) server that gives Claude (and other AI assistants) the ability to directly access and modify VBA code inside Excel workbooks (.xlsm, .xlsb, .xls, .xla, .xlam).

Why This Exists

If you've ever worked with Excel VBA and AI coding assistants, you know the pain:

1. Open VBA Editor, manually copy code
2. Paste into chat, ask AI for help
3. Copy AI's response back
4. Paste into VBA Editor, test, repeat...

VBA MCP Server eliminates this entirely. Claude can now read, write, create, delete, and backup VBA modules directly — just like it works with regular source code files.

Features

• Direct VBA Access — Read and write VBA code in-place, no export/import cycle
• Smart Workbook Handling — Detects already-open workbooks, avoids conflicts
• Auto-Save — Workbooks are saved automatically after writes
• Full Module Management — Create, delete, read, write, list, and backup modules
• Workbook Discovery — Find all .xlsm files in a directory tree
• Backup with Manifest — Export all modules to text files with JSON metadata
• Document Module Protection — Prevents accidental deletion of Sheet/ThisWorkbook modules
• Lightweight — Single Python file (~300 lines), two dependencies

Prerequisites

| Requirement | Details | |------------|---------| | OS | Windows (uses COM/Win32 API) | | Excel | Microsoft Excel (local installation) | | Python | 3.10 or later | | Trust Setting | See Excel Configuration below |

Installation

Option 1: pip install (Recommended)

pip install vba-mcp-server

Then add to your MCP config:

{
  "mcpServers": {
    "vba-mcp-server": {
      "command": "vba-mcp-server",
      "args": []
    }
  }
}

Option 2: Claude Code (Manual)

Add to your Claude Code MCP settings (~/.claude.json or project .mcp.json):

{
  "mcpServers": {
    "vba-mcp-server": {
      "command": "python",
      "args": ["C:/path/to/vba-mcp-server/server.py"],
      "env": {}
    }
  }
}

Option 3: Claude Desktop

Add to your Claude Desktop config (%APPDATA%/Claude/claude_desktop_config.json):

{
  "mcpServers": {
    "vba-mcp-server": {
      "command": "python",
      "args": ["C:/path/to/vba-mcp-server/server.py"]
    }
  }
}

Option 4: From Source

# Clone the repository
git clone https://github.com/xiongchenghou/vba-mcp-server.git
cd vba-mcp-server

# Create virtual environment (recommended)
python -m venv .venv
.venv\Scripts\activate

# Install dependencies
pip install -r requirements.txt

Excel Configuration

Required one-time setup — Excel must allow programmatic access to VBA:

1. Open Excel
2. Go to File > Options > Trust Center > Trust Center Settings
3. Click Macro Settings
4. Check "Trust access to the VBA project object model"
5. Click OK

Without this setting, all tools will return an error with a helpful hint message.

Available Tools

vba_list_modules

List all VBA modules in a workbook with metadata.

→ vba_list_modules("C:/Projects/MyWorkbook.xlsm")

[
  {"name": "Module1", "type": "StandardModule", "line_count": 342},
  {"name": "Sheet1",  "type": "Document",       "line_count": 15},
  {"name": "MyClass", "type": "ClassModule",     "line_count": 89}
]

vba_read_module

Read the source code of a specific module.

→ vba_read_module("C:/Projects/MyWorkbook.xlsm", "Module1")

' === Module: Module1 (StandardModule) ===
Sub HelloWorld()
    MsgBox "Hello from VBA!"
End Sub

vba_read_all

Read ALL modules at once — perfect for full codebase review.

→ vba_read_all("C:/Projects/MyWorkbook.xlsm")

============================================================
' Module: Module1
' Type: StandardModule
' Lines: 342
============================================================
[full source code...]

============================================================
' Module: Sheet1
' Type: Document
' Lines: 15
============================================================
[full source code...]

vba_write_module

Write or replace a module's code. Auto-saves the workbook. Creates the module if it doesn't exist.

→ vba_write_module("C:/Projects/MyWorkbook.xlsm", "Module1", "Sub Test()\n    MsgBox \"Updated!\"\nEnd Sub")

{"success": true, "module": "Module1", "lines_written": 3, "message": "Module 'Module1' updated (3 lines)"}

| Parameter | Type | Default | Description | |-----------|------|---------|-------------| | file_path | string | required | Path to the workbook | | module_name | string | required | Name of the module to write | | code | string | required | VBA source code | | create_if_missing | bool | true | Create module if it doesn't exist |

vba_create_module

Create a new VBA module (standard or class).

→ vba_create_module("C:/Projects/MyWorkbook.xlsm", "MyNewModule", "Option Explicit", "standard")

{"success": true, "module": "MyNewModule", "type": "StandardModule", "message": "Module 'MyNewModule' created"}

vba_delete_module

Delete a VBA module. Document modules (Sheet/ThisWorkbook) cannot be deleted — only their code can be cleared via vba_write_module.

→ vba_delete_module("C:/Projects/MyWorkbook.xlsm", "OldModule")

{"success": true, "message": "Module 'OldModule' deleted"}

vba_backup

Export all VBA modules to text files with a JSON manifest.

→ vba_backup("C:/Projects/MyWorkbook.xlsm")

{
  "success": true,
  "backup_dir": "C:/Projects/VBA_Backup/20260324_120000",
  "file_count": 8,
  "files": [
    {"name": "Module1", "type": "StandardModule", "file": "...", "lines": 342},
    ...
  ]
}

vba_list_workbooks

Find all .xlsm files in a directory.

→ vba_list_workbooks("C:/Projects", recursive=True)

[
  {"path": "C:/Projects/MyWorkbook.xlsm", "name": "MyWorkbook.xlsm", "size_kb": 245.3, "modified": "2026-03-24 12:00:00"},
  ...
]

Usage Examples

Refactoring VBA Code

"Read Module1 from MyWorkbook.xlsm, refactor the CalculateTotal function to handle edge cases, and write it back."

Claude will:

1. Call vba_read_module to get the current code
2. Analyze and refactor the function
3. Call vba_write_module to save the updated code

Code Review

"Read all VBA code from MyWorkbook.xlsm and review it for potential bugs, security issues, and best practices."

Claude will:

1. Call vba_read_all to get the complete codebase
2. Provide a comprehensive code review

Migration Assistance

"Read the VBA code from Legacy.xlsm and help me convert it to Python/JavaScript."

Claude will:

1. Call vba_read_all to understand the full VBA codebase
2. Analyze the business logic and data flow
3. Generate equivalent code in the target language

Batch Operations

"Find all .xlsm files in C:/Projects, list their modules, and backup everything."

Claude will:

1. Call vba_list_workbooks with recursive=True
2. Call vba_list_modules for each workbook
3. Call vba_backup for each workbook

How It Works

┌─────────────┐     stdio/MCP      ┌──────────────┐     COM/Win32      ┌─────────┐
│  Claude /    │ ◄────────────────► │  VBA MCP     │ ◄────────────────► │  Excel  │
│  AI Client   │   JSON-RPC 2.0    │  Server      │   pywin32          │  VBA    │
│             │                    │  (server.py) │                    │ Project │
└─────────────┘                    └──────────────┘                    └─────────┘

1. Claude sends tool calls via MCP (stdio transport)
2. VBA MCP Server receives the call, connects to Excel via COM
3. Excel provides access to the VBProject object model
4. Server reads/writes VBA code and returns results to Claude

Troubleshooting

"Trust access to the VBA project object model" error

Follow the Excel Configuration steps above. This is a one-time setting.

Excel is not responding

If Excel is busy (dialog box open, cell editing mode), COM calls will fail. Make sure Excel is idle before using the tools.

Module not found

Use vba_list_modules first to see available module names. Module names are case-sensitive.

File path issues

Use forward slashes (/) or escaped backslashes (\\) in file paths. The server normalizes paths automatically.

Cannot delete Sheet module

Sheet and ThisWorkbook modules are Document modules — they cannot be deleted from VBProject. Use vba_write_module with empty code to clear their contents instead.

Contributing

Contributions are welcome! Here are some ways you can help:

• Bug reports — Found an issue? Open an issue
• Feature requests — Have an idea? Let's discuss it
• Pull requests — Code improvements, new features, documentation
• Testing — Try it with different Excel versions and report results
• Documentation — Help improve the docs or add translations

Development Setup

git clone https://github.com/xiongchenghou/vba-mcp-server.git
cd vba-mcp-server
python -m venv .venv
.venv\Scripts\activate
pip install -r requirements.txt

# Run the server directly for testing
python server.py

Areas for Improvement

• [ ] UserForm support (read/write .frm files with controls)
• [ ] Diff-based editing (modify specific lines instead of full replacement)
• [ ] Excel cell/range read/write (beyond VBA code)
• [ ] Watch mode (detect VBA changes in real-time)
• [ ] Support for multiple simultaneous workbooks
• [ ] macOS support via alternative COM bridges

License

MIT — Use it freely, commercially or personally.

Star History

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Stop copy-pasting VBA code. Let AI work with it directly.