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MCP Python

Use the Python MCP SDK to create a toolset for Revit or an AutoCAD-family host. RevitDevTool discovers a Python toolset from a folder containing an entry file that matches *mcp.py. The entry file owns the toolset's package dependencies through PEP 723 metadata. Register the folder in Settings → MCP.

RevitDevTool pins the Python SDK to 2.1.1.

uv add "mcp==2.1.1"

What a Python toolset provides​

A toolset can expose tools, resources, and prompts to an AI client. Keep the public names and descriptions focused on the user task, and return structured data for model queries.

Create the toolset folder​

The sample uses revitdevtool_mcp.py at the root of the registered folder. The filename is flexible as long as it ends in mcp.py; keep the package folders beside it so normal Python imports work:

mcp_toolset/
├── revitdevtool_mcp.py       # discovery entry point + dependencies
├── tools/                    # @mcp.tool registrations
├── resources/                # @mcp.resource registrations
├── prompts/                  # @mcp.prompt registrations
├── dto/                      # request/response models
├── services/                 # host-facing application logic
└── shared/                   # shared helpers

Put the dependency declaration at the top of the *mcp.py entry file. RevitDevTool reads that file, resolves its PEP 723 metadata, then loads the module and its sibling packages. Do not put MCP toolset dependencies in conftest.py; that file belongs to pytest discovery, not MCP registration:

# revitdevtool_mcp.py
# /// script
# dependencies = [
#     "polars",
#     "xlsxwriter",
# ]
# ///
from mcp.server.mcpserver import MCPServer

mcp = MCPServer("Revit Python Toolset")

The entry file creates the server and imports registration functions from tools/, resources/, and prompts/. Each registration function receives the same mcp instance and adds its capabilities:

from tools.query_tools import register_query_tools
from resources.model_resources import register_model_resources

register_query_tools(mcp)
register_model_resources(mcp)

The user flow is:

  1. Create a folder with one *mcp.py entry file.
  2. Declare third-party packages in that entry file's PEP 723 header.
  3. Import the modules that register tools, resources, or prompts.
  4. Add the folder path in Settings → MCP.
  5. Wait for the catalog to reload, then verify the capabilities from the host MCP registry or an AI client.

The sample at samples/PythonDemo/mcp_toolset follows this pattern. unittest is not an alternative MCP toolset entry workflow; use the MCP entry file and its registered capabilities directly.

Runtime guidance​

  • Import host APIs only when the tool executes in the Autodesk host.
  • Keep tool parameters explicit and use snake_case names.
  • Describe read-only and model-changing behavior accurately.
  • Return structured results for element queries and summaries.
  • Keep Revit and AutoCAD-specific logic separate when their APIs differ.

For the MCP concepts and the default capabilities already provided by RevitDevTool, see MCP Protocol.

Official references: Python SDK documentation · Python SDK repository.