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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