TOM-MCP (Tabular Object Model - Model Context Protocol)

A Model Context Protocol (MCP) server that provides tools for reading and editing Power BI semantic models via the Tabular Object Model (TOM) v19+. This server exposes TMDL manipulation capabilities to Visual Studio Code Agent mode and other MCP-compatible clients.

Overview

TOM-MCP bridges the gap between Power BI's Tabular Object Model and modern AI-assisted development tools by implementing the Model Context Protocol. It enables AI assistants to understand, analyze, and modify Power BI semantic models programmatically.

Features

📊 Model Analysis

• List Tables: Enumerate all tables in a TMDL model
• List Measures: List all measures in a specific table
• Detect Unused Columns: Find columns not referenced by any measure or calculated column

✏️ Model Manipulation

• Add/Update Measures: Create new measures or modify existing ones
• Rename Objects: Rename tables, columns, or measures with automatic DAX reference updates
• Format Model: Deterministically format TMDL files for consistent Git diffs

✅ Validation

• Validate Model: Comprehensive model validation using Tabular Editor 2
  • Structural validation (TOM round-trip)
  • Best Practice Analyzer (BPA) checks
  • Progress streaming for long-running validations

🔧 Utilities

• Diff TMDL: Stream Git-style unified diffs between TMDL files
• List Tools: Discover available tools in the MCP server

Installation

Prerequisites

• .NET 8.0 or later
• Tabular Editor 2 (for validation features)
• Git (for diff functionality)

Setup

1. Clone the repository:

git clone https://github.com/yourusername/tom-mcp.git
cd tom-mcp

2. Build the project:

dotnet build

3. Configure Tabular Editor 2 (for validation):

# Run the setup script
.\setup-te2.ps1

Configuration

MCP Configuration (for VS Code)

Add to your .vscode/mcp.json:

{
  "servers": {
    "tom-mcp": {
      "command": "dotnet",
      "args": [
        "C:\\repos\\tom-mcp\\bin\\Release\\net9.0\\tom-mcp.dll"
      ],
      "env": {
        "ASPNETCORE_ENVIRONMENT": "Development"
      },
      "type": "stdio"
    }
  }
}

Available Tools

Model Information

• tmdl_list_tables - Lists all tables in a TMDL model
• tmdl_list_measures - Lists measures in a specific table
• tmdl_detect_unused_columns - Finds unreferenced columns

Model Modification

• addMeasure - Adds or updates a measure
• tmdl_rename_object - Renames objects and updates references
• tmdl_format_model - Formats model for consistent version control

Validation

• tmdl_validate_model - Comprehensive model validation with BPA

Utilities

• diff_tmdl - Compares two TMDL files
• list_tools - Lists all available tools

Usage Examples

Validating a Model

// In VS Code with GitHub Copilot
use #tmdl_validate_model to validate the model at "C:/MyModel/definition"

Adding a Measure

use #addMeasure to add a measure named "Total Sales" with formula "SUM(Sales[Amount])" to table "Measures" in "C:/MyModel/definition"

Renaming a Column

use #tmdl_rename_object to rename column "CustomerID" to "Customer ID" in table "Sales" at "C:/MyModel/definition"

Architecture

• Transport: Supports both stdio (for VS Code) and HTTP modes
• Framework: Built on MCP SDK 0.3.1-alpha
• Dependencies:
  • Microsoft.AnalysisServices.Tabular (TOM)
  • Tabular Editor 2 (for validation)

Development

Running in Debug Mode

dotnet run -- --stdio

Running Tests

# HTTP test endpoints available at:
# http://localhost:5000/test-echo
# http://localhost:5000/test-tmdl
# http://localhost:5000/test-validate

Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Submit a pull request

License

[Your License Here]

Acknowledgments

• Built with Model Context Protocol
• Powered by Tabular Object Model
• Validation by Tabular Editor