MCP server for Revit - Python

A pyRevit-oriented implementation of the Model Context Protocol (MCP) for Autodesk Revit

Related MCP server: Revit MCP Server

Local pairing and Autodesk Marketplace publication

This project is being prepared for Autodesk Marketplace review; it is not yet certified. The review candidate retains all 20 tools, including Python execution. See publication requirements and outstanding gates, privacy information, and security boundaries.

After installing the pyRevit extension, choose MCP > Bridge > Connect in Revit to consent and create an encrypted pairing secret for your Windows user. Choose Disconnect to revoke it. Requests that change models and Python execution show their payload for review in Revit before proceeding. Pairing also permits local Revit discovery and launch. Pairing is shared across Revit instances for the same Windows user; select the correct Routes port before connecting.

The MCP-to-Revit bridge accepts only loopback hosts. Remote VM/LAN HTTP bridges are rejected. Optional HTTP MCP transports require a paired bearer header; stdio is the recommended publication transport and needs no token in client configuration. Do not expose either listener to a network, tunnel or the internet.

How?

• This minimal implementation leverages the Routes module inside pyRevit to create a bridge between Revit and Large Language Models (LLMs).

• It provides a straightforward template to get started quickly, letting you prototype and iterate tools to give LLMs access to your Revit models.

• These tools are designed to be expanded for your specific use cases. You're very welcome to fork the repo and make your own contributions.

• Note: The pyRevit Routes API is currently in draft form and subject to change. This extension authenticates its own routes using Windows-user pairing. Other pyRevit routes/extensions remain outside this protection; review pyRevit server binding and the security document.

Batteries Included

This repo is aimed at:

• Beginners to the Revit API

• Python specialists who aren't versed in C#

• Anyone wanting to prototype and iterate quickly with LLMs and Revit

It contains:

• A complete Routes implementation for pyRevit

• A minimal MCP server script to connect to any MCP-compatible client

• Several test commands to get you started right away

Key Architecture Components

The system runs as two separate servers working together in a chain:

Claude / LLM Client
       |
       |  MCP Protocol (stdio or HTTP)
       v
  main.py  (MCP Server)
       |
       |  HTTP requests (localhost:48884)
       v
  pyRevit Routes  (REST API running inside Revit)
       |
       |  Revit API calls
       v
  Revit Application

main.py is the MCP server. It speaks the MCP protocol so that Claude (or any MCP-compatible client) can call tools. When a tool is called, main.py translates it into an HTTP request and forwards it to Revit.

pyRevit Routes is a lightweight REST API that runs inside the Revit process. It receives those HTTP requests, executes Revit API code (since it has direct access to the running instance), and returns JSON responses.

They never conflict because they serve different roles, speak different protocols, and listen on different ports.

Note: The Launch & Document tools (launch_revit, list_revit_installations) are the exception — they run entirely on the MCP side, using subprocess to start Revit and then polling the pyRevit Routes health endpoint until the bridge is ready.

1. MCP Server (main.py):

• Built with FastMCP

• Handles HTTP communication with Revit Routes API

• Registers tools from modular tool system

• Provides helper functions for GET/POST/Image requests

2. pyRevit Extension (revit-mcp-python.extension/):

• Contains the Routes API that runs inside Revit

• Modular route registration in startup.py

• Individual route modules in revit_mcp/ directory

3. Tool Registration System (tools/):

• Modular tool organization by functionality

• Central registration through tools/__init__.py

• Each module registers its own tools with the MCP server

Supported Tools

Current Implementation Status

Getting Started

Installing uv:

Refer to ./README_UV.md

Installing the Extension on Revit

Activate pyRevit Routes

1. In Revit, navigate to the pyRevit tab

2. Open Settings

3. Go to Routes > activate Routes Server pyRevit will start listening on port http://localhost:48884/

Install from pyRevit:

1. In Revit, navigate to the pyRevit tab

2. Open Extensions

3. Select the MCP Server for Revit Python Extension > Install extension

4. Select location, default is %APPDATA%\Roaming\pyRevit\Extensions

5. Enable and wait for pyRevit to reload. Restart Revit if necessary.

Manual Installation on a custom directory:

1. Clone the repo in a custom location:

   git clone https://github.com/mcp-servers-for-revit/mcp-server-for-revit-python

2. Add .extension to the root folder name

3. In Revit, navigate to the pyRevit tab

4. Open Settings

5. Under "Custom Extensions", add the path to the .extension folder

6. Save settings and reload pyRevit (you might need to restart Revit entirely)

Testing Your Connection

Once installed, test that the Routes API is working:

1. Choose MCP > Bridge > Connect in Revit, then run this authenticated check from the exact candidate directory (a browser request has no pairing header and is denied):

   uv run --frozen python -c "import anyio; from main import revit_get; print(anyio.run(revit_get, '/status/'))"

2. If successful, you should see a response like:

   {"status": "active",
    "health": "healthy",
    "revit_available": true,
    "document_title": "your_revit_filename",
    "api_name": "revit_mcp"}

The Routes Service will now load automatically whenever you start Revit. To disable it, simply remove the extension path from the pyRevit settings.

Using the MCP Client

Testing with the MCP Inspector

The MCP SDK includes a handy inspector tool for debugging:

mcp dev main.py

Then access http://127.0.0.1:6274 in your browser to test your MCP server interactively.

Transport Modes

The MCP server supports multiple transport modes for different use cases:

Running with combined transport (recommended for HTTP):

uv run --frozen main.py --combined

After pairing, this starts the authenticated server on http://127.0.0.1:8000 with both SSE and streamable-HTTP endpoints available.

The following unpaired requests return HTTP 401. HTTP clients must include the header returned by revit_mcp.pairing.authorization_headers(); prefer stdio to avoid copying a secret into client configuration.

Testing the endpoints:

# Test streamable-http
curl -X POST http://localhost:8000/mcp

# Test SSE
curl http://localhost:8000/sse

Connecting to Claude Desktop

The simplest way to install your MCP server in Claude Desktop:

mcp install main.py

Or for manual installation:

1. Open Claude Desktop → Settings → Developer → Edit Config

2. Add this to the mcpServers section:

{
  "mcpServers": {
    "Revit Connector": {
      "command": "uv",
      "args": [
        "run",
        "--frozen",
        "mcp",
        "run",
        "/absolute/path/to/main.py"
      ]
    }
  }
}

For HTTP transport mode, the following URL-only example must also be accompanied by the paired Authorization header in a client that supports it:

{
  "mcpServers": {
    "Revit Connector": {
      "url": "http://localhost:8000/mcp"
    }
  }
}

Connecting to Claude Code

claude mcp add -s user "Revit-Connector" -- uv run --frozen mcp run /absolute/path/to/main.py

Creating Your Own Tools

The modular architecture of this project makes adding functionalities relatively simple. The provided LLM.txt file also gives your language model the necessary context to get started right away.

The process involves three main parts:

Part 1: Create the Route Module in Revit

Create a new Python file within the revit-mcp-python.extension/revit_mcp/ directory (e.g., revit_mcp/your_module.py). This module will contain all the related functions you want to expose.

# In revit-mcp-python.extension/revit_mcp/your_module.py

# -*- coding: UTF-8 -*-
"""
Your Module for Revit MCP
Handles your specific functionality.
"""
from pyrevit import routes, revit, DB
import json
import logging

# Standard logger setup
logger = logging.getLogger(__name__)

def register_your_routes(api):
    """Register all your routes with the API."""

    # ---- Example 1: A GET request for reading data ----
    @api.route('/your_endpoint/', methods=["GET"])
    def get_project_title(doc):
        """Gets the project title from the Revit model."""
        try:
            value = doc.Title
            return routes.make_response(data={"status": "success", "data": value})
        except Exception as e:
            logger.error("Get project title failed: {}".format(str(e)))
            return routes.make_response(data={"error": str(e)}, status=500)

    # ---- Example 2: A POST request for modifying the model ----
    @api.route('/modify_model/', methods=["POST"])
    def modify_model(doc, request):
        """Handles POST requests for modifying the Revit model."""
        try:
            data = json.loads(request.data) if isinstance(request.data, str) else request.data

            # Use a transaction for all model modifications
            t = DB.Transaction(doc, "Modify Model via MCP")
            t.Start()

            try:
                element_id = data.get("element_id")
                new_value = data.get("new_value")
                element = doc.GetElement(DB.ElementId(int(element_id)))
                param = element.LookupParameter("Comments")
                param.Set(new_value)

                t.Commit()
                return routes.make_response(data={"status": "success", "result": "Element modified."})

            except Exception as tx_error:
                if t.HasStarted() and not t.HasEnded():
                    t.RollBack()
                raise tx_error

        except Exception as e:
            logger.error("Modify model failed: {}".format(str(e)))
            return routes.make_response(data={"error": str(e)}, status=500)

    logger.info("Your custom routes were registered successfully.")

Part 2: Create the MCP Tool Module

Create the corresponding tools for the MCP server in the tools/ directory (e.g., tools/your_tools.py). This module will use the revit_get and revit_post helpers from main.py.

# In tools/your_tools.py
# -*- coding: utf-8 -*-
"""Your tools for the MCP server."""

from mcp.server.fastmcp import Context
from .utils import format_response

def register_your_tools(mcp, revit_get, revit_post, revit_image=None):
    """Register your tools with the MCP server."""

    # ---- Tool for the GET request ----
    @mcp.tool()
    async def get_revit_project_title(ctx: Context) -> str:
        """
        Retrieves the title of the currently open Revit project.
        """
        response = await revit_get("/your_endpoint/", ctx)
        return format_response(response)

    # ---- Tool for the POST request ----
    @mcp.tool()
    async def modify_revit_element_comment(
        element_id: int,
        new_value: str,
        ctx: Context = None
    ) -> str:
        """
        Modifies the 'Comments' parameter of a specific element.

        Args:
            element_id: The ID of the element to modify.
            new_value: The new comment to apply to the element.
        """
        payload = {"element_id": element_id, "new_value": new_value}
        response = await revit_post("/modify_model/", payload, ctx)
        return format_response(response)

Part 3: Register Your New Modules

1. Register the Route Module

Open revit-mcp-python.extension/startup.py and add your new route registration function.

# In revit-mcp-python.extension/startup.py

# ... (other imports)
# Import the registration function from your new module
from revit_mcp.your_module import register_your_routes

def register_routes():
    """Register all MCP route modules"""
    api = routes.API('revit_mcp')
    try:
        # ... (existing route registrations)

        # Register your new routes (this registers all functions inside)
        register_your_routes(api)

        logger.info("All MCP routes registered successfully")
    except Exception as e:
        logger.error("Failed to register MCP routes: {}".format(str(e)))
        raise

2. Register the Tool Module

Open tools/__init__.py and add your new tool registration function.

# In tools/__init__.py

# ... (other tool imports)
# Import the registration function from your new tool module
from .your_tools import register_your_tools

def register_tools(mcp_server, revit_get_func, revit_post_func, revit_image_func):
    """Register all tools with the MCP server"""

    # ... (existing tool registrations)
    # Register your new tools (this registers all tools inside)
    register_your_tools(mcp_server, revit_get_func, revit_post_func, revit_image_func)

    return mcp_server

Roadmap

This is a work in progress and more of a demonstration than a fully-featured product. Future improvements could include:

• Creating a Client inside Revit

• Implementing compatibilities with other language Models

• Authentication and security enhancements

• More advanced Revit tools and capabilities

• Better error handling and debugging features

• Benchmarking with local models

• Documentation and examples for common use cases

• ...

Contributing

Contributions are welcome! Feel free to submit pull requests or open issues for any bugs or feature requests. Feel free to reach out to me if you have any questions, ideas