DAX Formatter MCP Server

A Model Context Protocol (MCP) server that provides DAX (Data Analysis Expressions) formatting capabilities to AI assistants and other MCP clients. This server integrates with the official DAX Formatter service by SQLBI to deliver professional-grade DAX code formatting.

🚀 Features

Single DAX Expression Formatting: Format individual DAX expressions with professional standards
Batch Processing: Format multiple DAX expressions in a single efficient request
Comprehensive Formatting Options: Control line length, spacing, separators, and more
Error Handling: Robust error handling with detailed error messages
Fallback Mechanisms: Automatic fallback to individual formatting if batch processing fails
Database Context: Support for database and server context (anonymized for privacy)

📋 Prerequisites

.NET 8.0 Runtime or higher
Internet connection (communicates with daxformatter.com)
MCP-compatible client (Claude Desktop, Continue, or custom MCP client)

🛠️ Installation

Option 1: Download Release (Recommended)

Download the latest release from the Releases page
Extract the archive to your preferred location
Note the path to the executable for configuration

Option 2: Build from Source

# Clone the repository
git clone https://github.com/EmanueleMeazzo/dax-formatter-mcp.git
cd dax-formatter-mcp

# Build the project
dotnet build --configuration Release

# The executable will be in bin/Release/net8.0/

⚙️ Configuration

Claude Desktop

Add the following to your Claude Desktop configuration file:

Windows: %APPDATA%\Claude\claude_desktop_config.json
macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
Linux: ~/.config/claude/claude_desktop_config.json

{
  "mcpServers": {
    "dax-formatter": {
      "command": "path/to/dax-formatter-mcp.exe",
      "args": []
    }
  }
}

Continue IDE Extension

Add to your Continue configuration:

{
  "mcpServers": [
    {
      "name": "dax-formatter",
      "command": "path/to/dax-formatter-mcp.exe",
      "args": []
    }
  ]
}

Generic MCP Client

For any MCP client supporting the MCP 2024-11-05 protocol:

{
  "servers": [
    {
      "name": "dax-formatter",
      "transport": {
        "type": "stdio",
        "command": "path/to/dax-formatter-mcp.exe",
        "args": []
      }
    }
  ]
}

Using with .NET Runtime

If you prefer to use the DLL with the .NET runtime:

{
  "mcpServers": {
    "dax-formatter": {
      "command": "dotnet",
      "args": ["path/to/dax-formatter-mcp.dll"]
    }
  }
}

📖 Usage

Once configured, you can use the DAX formatter through your MCP client:

Basic Usage

Format this DAX expression:
CALCULATE(SUM(Sales[Amount]),FILTER(Products,Products[Category]="Electronics"))

Multiple Expressions

Format these DAX measures:
1. [Total Sales] := SUM(Sales[Amount])
2. [Electronics Sales] := CALCULATE(SUM(Sales[Amount]),Products[Category]="Electronics")
3. [Sales YTD] := TOTALYTD(SUM(Sales[Amount]),'Calendar'[Date])

With Formatting Options

Format this DAX with short lines and specific separators:
CALCULATE(SUM(Sales[Amount]),FILTER(Products,Products[Category]="Electronics"))

Options:
- Line length: ShortLine
- List separator: ;
- Decimal separator: ,

🔧 Available Tools

`format_dax`

Formats a single DAX expression.

Parameters:

dax (required): The DAX expression to format
options (optional): Formatting options object

Example:

{
  "dax": "CALCULATE(SUM(Sales[Amount]),FILTER(Products,Products[Category]=\"Electronics\"))",
  "options": {
    "maxLineLength": "LongLine",
    "skipSpaceAfterFunctionName": "BestPractice"
  }
}

`format_dax_multiple`

Formats multiple DAX expressions in a single request.

Parameters:

expressions (required): Array of DAX expressions to format
options (optional): Formatting options object

Example:

{
  "expressions": [
    "CALCULATE(SUM(Sales[Amount]),FILTER(Products,Products[Category]=\"Electronics\"))",
    "[Total Sales] := SUM(Sales[Amount])"
  ],
  "options": {
    "maxLineLength": "LongLine",
    "databaseName": "SalesDB",
    "serverName": "ProductionServer"
  }
}

🎛️ Formatting Options

All formatting options are optional and have sensible defaults:

Option	Values	Default	Description
`maxLineLength`	`ShortLine`, `LongLine`, `VeryLongLine`	`LongLine`	Maximum line length for formatted code
`skipSpaceAfterFunctionName`	`BestPractice`, `False`	`BestPractice`	Spacing after function names
`listSeparator`	Any character	`,`	Character used as list separator
`decimalSeparator`	Any character	`.`	Character used as decimal separator
`databaseName`	String	-	Database name for context (anonymized)
`serverName`	String	-	Server name for context (anonymized)

📝 Example DAX Expressions

Here are some example DAX expressions you can test with:

Basic Measures

[Total Sales] := SUM(Sales[Amount])

Complex Calculations

CALCULATE(SUM(Sales[Amount]),FILTER(ALL(Products),Products[Category]="Electronics"),USERELATIONSHIP(Sales[OrderDate],'Calendar'[Date]))

Time Intelligence

[Sales YTD] := TOTALYTD(SUM(Sales[Amount]),'Calendar'[Date])

Table Expressions

EVALUATE FILTER(Customer, Customer[Country] = "USA")

🔍 Troubleshooting

Common Issues

Server fails to start:

Ensure .NET 8.0 runtime is installed
Check that the executable path is correct in your configuration
Verify you have internet connectivity (required for DAX Formatter service)

Formatting requests fail:

Check your internet connection
Verify the DAX syntax is valid
Try with simpler expressions first

MCP client doesn't recognize the server:

Restart your MCP client after adding the configuration
Check the JSON configuration syntax
Verify the executable path is absolute and correct

Debug Mode

To enable debug logging, you can run the server manually to see detailed logs:

# Run the server directly to see debug output
./dax-formatter-mcp.exe

Then send JSON-RPC messages manually to test functionality.

🏗️ Architecture

The MCP server is built with:

.NET 9.0: Modern, cross-platform runtime
DAX Formatter Client: Official NuGet package from SQLBI
JSON-RPC 2.0: Standard protocol for MCP communication
Async/Await: Non-blocking I/O for better performance

Flow Diagram

MCP Client → JSON-RPC → DAX Formatter MCP Server → DAX Formatter API → Formatted DAX

🤝 Contributing

Contributions are welcome! Please follow these steps:

Fork the repository
Create a feature branch (git checkout -b feature/amazing-feature)
Make your changes
Add tests if applicable
Commit your changes (git commit -m 'Add amazing feature')
Push to the branch (git push origin feature/amazing-feature)
Open a Pull Request

Development Setup

# Clone the repository
git clone https://github.com/EmanueleMeazzo/dax-formatter-mcp.git
cd dax-formatter-mcp

# Restore dependencies
dotnet restore

# Build the project
dotnet build

# Run tests
dotnet test

🔒 Privacy & Security

All DAX expressions are sent to the official DAX Formatter service at daxformatter.com
Database and server names are anonymized by the DAX Formatter client
No DAX expressions are stored locally
No personal information is collected or transmitted

📜 License

This project is licensed under the MIT License - see the LICENSE file for details.

🙏 Acknowledgments

SQLBI for the excellent DAX Formatter service
Anthropic for the Model Context Protocol specification
Microsoft for the DAX language