Revit MCP Server

A Model Context Protocol (MCP) server that connects Autodesk Revit 2025+ to AI assistants like Claude. Query elements, create views, manage sheets, and modify parameters — all through natural language.

How It Works

The system has two halves that communicate over a named pipe:

Claude Desktop / VS Code
        │
        │ stdio (JSON-RPC)
        ▼
┌─────────────────┐          Named Pipe           ┌──────────────────┐
│  RevitMcp.Server │  ◄──── "revit-mcp-bridge" ──► │  RevitMcp.Addin  │
│  (Console App)   │     length-prefixed JSON      │  (Revit Add-in)  │
└─────────────────┘                                └──────────────────┘
                                                           │
                                                    Revit API calls
                                                    (main thread only)

RevitMcp.Server is a standalone console app that speaks MCP over stdio. Claude Desktop launches it automatically.

RevitMcp.Addin loads inside Revit, runs a named-pipe listener on a background thread, and marshals all Revit API calls to the main thread via ExternalEvent.

RevitMcp.Core contains the shared contracts, command names, and handler implementations used by both sides.

Available Tools

Elements

Views

Sheets

Model & Project

Prerequisites

• Autodesk Revit 2025 (or newer)
• .NET 8 SDK — download here
• Claude Desktop or another MCP-compatible client

Building

Build the entire solution:

dotnet build RevitMcpServer.sln -c "Debug R25"

Build the server only:

dotnet build src/RevitMcp.Server/RevitMcp.Server.csproj

Publish the server for deployment:

dotnet publish src/RevitMcp.Server -c Release -o ./publish

The add-in’s post-build step automatically copies the DLL and .addin manifest to Revit’s add-in folder.

Setup

1. Install the Revit Add-in

Build the RevitMcp.Addin project with a Revit 2025 configuration (Debug R25 or Release R25). The post-build event copies the output to:

%APPDATA%\Autodesk\REVIT\Addins\2025\RevitMcp.Addin\

2. Configure Claude Desktop

Add the server to your Claude Desktop config (claude_desktop_config.json):

{
  "mcpServers": {
    "revit-mcp": {
      "command": "dotnet",
      "args": ["run", "--project", "C:\\path\\to\\src\\RevitMcp.Server\\RevitMcp.Server.csproj"]
    }
  }
}

Or if you’ve published the server:

{
  "mcpServers": {
    "revit-mcp": {
      "command": "C:\\path\\to\\publish\\RevitMcp.Server.exe"
    }
  }
}

3. Launch

1. Open Revit — the add-in loads automatically and starts the pipe server
2. Open Claude Desktop — it spawns the MCP server process on first tool call
3. The MCP Status button on the ribbon turns green when connected

Ribbon Buttons

The add-in creates a Revit MCP ribbon panel with four buttons:

The MCP Status icon changes color based on connection state: green (connected), yellow (waiting), red (error).

Solution Structure

RevitMcpServer.sln
├── RevitMcp.Core/           Shared library (no MCP SDK or Revit UI dependency)
│   ├── Commands/            Command name constants
│   ├── Handlers/            ICommandHandler implementations (one per tool)
│   └── Messages/            BridgeRequest / BridgeResponse records
│
├── RevitMcp.Server/         MCP server (stdio transport, console app)
│   ├── Bridge/              Named pipe client (RevitBridgeClient)
│   └── Tools/               [McpServerToolType] tool definitions
│
└── RevitMcp.Addin/          Revit add-in (named pipe server, ribbon UI)
    ├── Bridge/              PipeServer, RequestChannel, ExternalEventExecutor
    ├── Status/              McpStatusTracker (connection state singleton)
    └── UI/                  Ribbon button commands

Adding a New Tool

1. Add the command name to RevitMcp.Core/Commands/CommandNames.cs
2. Create an ICommandHandler in RevitMcp.Core/Handlers/
3. Create or update a [McpServerToolType] class in RevitMcp.Server/Tools/
4. Register the handler in RevitMcp.Addin/App.cs

Key Design Decisions

• Named pipe bridge — The MCP server and Revit run in separate processes. A named pipe (revit-mcp-bridge) with 4-byte length-prefixed JSON framing connects them.
• ExternalEvent threading — All Revit API calls must run on Revit’s main thread. Requests queue through a Channel and execute via ExternalEvent.
• System.Text.Json — Used everywhere for serialization. No Newtonsoft.Json dependency.
• Preview-mode deletes — delete_elements defaults to dry-run. The AI must explicitly set confirm=true to mutate the model.

License

All rights reserved.