Protocol

The Model Context Protocol (MCP) is a standard way for an AI client to discover and use capabilities exposed by a server. RevitDevTool uses the protocol to connect an AI client to running Revit or AutoCAD-family hosts.

• MCP
• Cursor
• Claude
• GitHub Copilot
• Codex

Any MCP 2.0 client

Any client that supports MCP 2.0 can connect. Read the latest protocol specification.

Official SDKs

RevitDevTool pins the SDK versions used by its two toolset entry points:

SDK	Pinned version	Official documentation
.NET SDK	2.3.0	C# SDK Getting Started · C# SDK repository
Python SDK	2.3.0	Python SDK documentation · Python SDK repository

For the protocol itself, see the official MCP specification.

Core concepts

MCP concept	Meaning
Client	The AI application, such as Cursor, Claude, GitHub Copilot or Codex
Server	The local RevitDevTool MCP service that connects the client to hosts
Tool	An operation the client can call, such as querying a model or opening a document
Resource	Readable context identified by a URI, such as model state or an API cheatsheet
Prompt	A reusable instruction template exposed to the client

The normal user-facing flow is: connect the client, list running hosts, then write one code_mode program that searches the host's capabilities, calls the best match, and returns only the result you need.

The MCP view

The MCP toggle in the panel shows a list of every tool the host can offer: the built-in ones and those from the .NET and Python toolsets you load. It shows how many tools each source provides, how often each was called, and lets you search by name.

Use Load .NET Toolset and Load Python Toolset at the bottom to add a toolset.

Settings only lists and removes sources

Toolsets are added from the MCP view. Settings → MCP lists the sources you have loaded under Custom Loaded Sources and lets you remove them.

Tools your client sees

The MCP service exposes a small, fixed tool list:

Tool	Purpose
list_processes	Show running Revit and AutoCAD-family instances
launch_host	Start a supported host instance
read_file_info	Read metadata and a safe summary for a local file
code_mode	Run a short C# program that searches, describes, invokes, and reads host capabilities

The list does not change when you register toolsets. Host and toolset capabilities are reached from inside code_mode, not added to the client's tool list.

Host capabilities

code_mode searches the catalog of the selected host. Typical built-in capabilities are:

Capability	Purpose
execute_csharp_code	Run C# code in the host context
execute_python_code	Run Python code in the host context
open_document	Open a document in the host
navigate_history	Move backward or forward through supported model changes
view_screenshot	Capture the current host view for visual inspection

Specialized capabilities and registered toolsets are preferred over the code-execution fallbacks. Pass readOnly: true to code_mode to block any capability that is not marked read-only. The exact entries depend on which host is running and which toolsets are registered.

Default resources

RevitDevTool provides host reference and context resources. The available set depends on the connected host:

Host	Resource URI	Purpose
Revit	revit://python-cheatsheet	Revit Python usage guidance
Revit	revit://csharp-cheatsheet	Revit C# usage guidance
Revit	revit://model/context	Current model context and summary
Revit	revit://model/warnings	Current model warnings
Revit	revit://version	Host and API version information
AutoCAD-family	acad://python-cheatsheet	AutoCAD Python usage guidance
AutoCAD-family	acad://csharp-cheatsheet	AutoCAD C# usage guidance

These resources are read-only context. Registered .NET or Python toolsets may add additional tools and resources for their own domain.

Default prompts

The local service exposes:

• revit_code for Revit code-generation guidance;
• acad_code for AutoCAD-family code-generation guidance.

.NET and Python toolsets

RevitDevTool accepts both compiled .NET assemblies and Python toolset folders containing a *mcp.py entry file. The entry file carries its own PEP 723 dependency metadata; its capabilities appear alongside the defaults when the relevant host is running.

Use MCP .NET or MCP Python for registration guidance.