# RevitMCPBridge

"Teaching AI to Build"

## Episode 2: Building the Bridge

Connecting two worlds that were never meant to talk

CLAUDE
REVIT

## THE CHALLENGE

### CLAUDE

- Runs in cloud
- Text in/out
- No file access
- Stateless

### REVIT

- Runs on desktop
- GUI-based
- C#/.NET
- Stateful

How do you make these talk to each other?

## THE KEY INSIGHT

### Model Context Protocol (MCP)

CLAUDE
JSON ─►
MCP
SERVER
─► JSON
TOOL

Anthropic built MCP so Claude could use external tools.
We just needed to make Revit... a tool.

## THE ARCHITECTURE

LAYER 1: Claude Code
User ─► "Create a 20x30 room" ─► Claude Code (WSL)
│ stdio
LAYER 2: MCP Server (Python)
Translates MCP calls ─► Named Pipe messages
│ Named Pipe
LAYER 3: Revit Add-in (C#)
Receives JSON ─► Executes Revit API ─► Returns data

## NAMED PIPES

A persistent communication channel in Windows

\\.\pipe\RevitMCPBridge2026
{"method":"createWall",...} ─►
◄─ {"success":true,"wallId":12345}

Messages flow both directions. Instantly.

## INSIDE REVIT: THE ADD-IN

MCPServer.cs
Listen
on Pipe
►
Parse
JSON
►
Route
Method
▼
WallMethods │ ViewMethods │ SheetMethods │ ...
▼
REVIT API

## THE FIRST TEST

$ echo '{"method":"ping"}' | nc -U /pipe/RevitMCP2026
{"success": true, "result": "pong"}
$ _
IT WORKS.

## ANATOMY OF A COMMAND

{
"method": "createWall", // What to do
"params": { // How to do it
"startPoint": [0, 0, 0],
"endPoint": [20, 0, 0],
"levelId": 30,
"height": 10
}
}

Plain JSON. Human readable. Machine executable.

## FIRST METHODS

November 2024

ping
getLevels
getProjectInfo
getWallTypes
createWall
getViews
getElements
getSheets

~30 methods total

Enough to prove the concept.

## THE REVIT CONTEXT CHALLENGE

REVIT'S RULE: All API calls must happen on
Revit's main thread

External command

─► Direct API access ✓

Named pipe listener

─► Background thread ✗

SOLUTION: ExternalEvent + IExternalEventHandler

Queue commands, execute on main thread

## THE BRIDGE: COMPLETE

CLAUDE
═══════════►
REVIT

Natural language in. BIM model changes out.

52,400
Lines of C#
41
Source Files
30
Methods

## Next Episode:

# "First Autonomous Breakthrough"

December 2024.
30 walls appeared in Revit.

No human touched the mouse.

BIM Ops Studio

www.bimopsstudio.com

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