AutoCAD 2027 MCP Server: fix and setup for AI agents (Claude, Cursor)

AutoCAD 2027 MCP Server: how to make it work with AI agents (Claude, Cursor, etc.)

TL;DR. The MCP server bundled with AutoCAD 2027 (offered by the installer as "Autodesk AutoCAD MCP Server") does not work out of the box in build 26.0.460.2523:

1. ModelContextProtocol.AspNetCore.dll is missing from the plugin folder → MCPHTTPSTART throws FileNotFoundException.
2. The HTTP server is disabled by default (enableHttpServer: false).
3. The plugin is not loaded at startup → commands MCPCONFIG / MCPHTTPSTART are "unknown" until you NETLOAD it.

After the fixes below, the server listens on http://localhost:5001/mcp (Streamable HTTP) and works with any MCP client.

Tested on Windows 11, AutoCAD 2027 (26.0.460.2523), Russian UI.

How it works

• The server is a .NET plugin running inside acad.exe; it only works while AutoCAD is open.
• Plugin folder: C:\Program Files\Autodesk\ApplicationPlugins\AutoCAD-MCP-Server-2027.bundle\Contents\
• AutoCAD commands: MCPCONFIG (Show / Modify / Write / Load / Reset), MCPHTTPSTART, MCPHTTPSTOP.
• Endpoint: http://localhost:/mcp, the first free port in a range (usually 5001).
• Server name autodesk-autocad-mcp-server. Tools include queryAutoCADObjects, discoverAutoCADTypes, aggregateAutoCADObjects, checkAutoCADObjects, manipulateDrawingCanvas.

Step 1. Add the missing DLL

Symptom when running MCPHTTPSTART:

System.IO.FileNotFoundException: Could not load file or assembly
'ModelContextProtocol.AspNetCore, Version=0.4.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'
   at Autodesk.AutoCAD.Mcp.Http.HttpMcpServer.StartServer()

ASP.NET Core 10 itself is already referenced by AutoCAD (acdbmgd.runtimeconfig.json lists Microsoft.AspNetCore.App 10.0.0); only the MCP SDK's ASP.NET Core package is missing.

1. Find the exact SDK version shipped with the plugin (2027: 0.4.0-preview.3):

   (Get-Item "C:\Program Files\Autodesk\ApplicationPlugins\AutoCAD-MCP-Server-2027.bundle\Contents\ModelContextProtocol.Core.dll").VersionInfo.ProductVersion

2. Download the same version of the official package from NuGet (ModelContextProtocol.AspNetCore 0.4.0-preview.3) into an empty folder and unzip it:

   Invoke-WebRequest https://www.nuget.org/api/v2/package/ModelContextProtocol.AspNetCore/0.4.0-preview.3 -OutFile pkg.zip
   Expand-Archive pkg.zip x

3. Verify x\lib\net10.0\ModelContextProtocol.AspNetCore.dll: [Reflection.AssemblyName]::GetAssemblyName("").FullName must show Version=0.4.0.0, PublicKeyToken=cc7b13ffcd2ddd51, and its ProductVersion must have the same commit hash as ModelContextProtocol.Core.dll. (The NuGet DLL has no Authenticode signature; Autodesk re-signs its copies. This is expected.)
4. Copy it into the plugin's Contents folder (requires admin):

   Copy-Item x\lib\net10.0\ModelContextProtocol.AspNetCore.dll "C:\Program Files\Autodesk\ApplicationPlugins\AutoCAD-MCP-Server-2027.bundle\Contents\"

An AutoCAD update may remove the file or change the SDK version; repeat this step if the error comes back.

Step 2. Enable the HTTP server in the config

The config file path comes from the environment variable ACMCP_TOOLS_CONFIG_FILE. Without it, MCPCONFIG Write/Load refuse to work.

1. Set the variable, then restart AutoCAD:

   setx ACMCP_TOOLS_CONFIG_FILE "%APPDATA%\Autodesk\acmcp-config.json"
   

2. Write the file in exactly this format (nested toolsConfiguration, camelCase). A flat or PascalCase file is silently ignored by Load:

{
  "toolsConfiguration": {
    "enabledTools": [],
    "disabledTools": [],
    "enableAllToolsByDefault": true,
    "enableExperimentalFeatures": false,
    "enableDebugLogging": false,
    "enableHttpServer": true,
    "jsonCompression": {
      "enableObjectDeduplication": false,
      "maxPropertyCountForObjectDeduplication": 4,
      "minOccurrenceForObjectDeduplication": 2,
      "enableStringDeduplication": false,
      "enableArrayCompression": true,
      "enabled": true,
      "arrayCompressionMinSize": 3,
      "arrayCompressionMaxSparsity": 0.5,
      "arrayCompressionMinSimilarity": 0.7
    }
  }
}

MCPCONFIG → Show prints the current JSON; Write saves it to the file. Use either as the reference format.

Step 3. Start the server (after every AutoCAD launch)

In the AutoCAD command line (not PowerShell):

1. NETLOAD → C:\Program Files\Autodesk\ApplicationPlugins\AutoCAD-MCP-Server-2027.bundle\Contents\acmcp.dll
2. MCPCONFIG → Load → Configuration imported successfully from: ...
3. MCPHTTPSTART → AutoCAD MCP Server is ... running on http://localhost:5001/mcp

Automated via COM. Run it in Windows PowerShell 5.1 (powershell.exe), because PowerShell 7 has no Marshal.GetActiveObject. Pass all prompt answers in a single SendCommand string, otherwise the COM call blocks at the first prompt.

function Retry([scriptblock]$b) {
    for ($k = 0; $k -lt 60; $k++) { try { return & $b } catch { Start-Sleep 1 } }
    throw "AutoCAD not ready"
}
$ac = Retry { [Runtime.InteropServices.Marshal]::GetActiveObject("AutoCAD.Application") }
if ((Retry { $ac.Documents.Count }) -eq 0) { [void](Retry { $ac.Documents.Add() }); Start-Sleep 3 }
$d = Retry { $ac.ActiveDocument }
$dll = "C:\Program Files\Autodesk\ApplicationPlugins\AutoCAD-MCP-Server-2027.bundle\Contents\acmcp.dll"
Retry { $d.SendCommand("(setvar `"FILEDIA`" 0)`n_NETLOAD`n`"$dll`"`n(setvar `"FILEDIA`" 1)`n_MCPCONFIG`n_Load`n_MCPHTTPSTART`n") }

Check that the port is open: Get-NetTCPConnection -State Listen -OwningProcess (Get-Process acad).Id.

Step 4. Connect your MCP client

Claude Code (.mcp.json in the project root). Any client that supports Streamable HTTP can use the same URL:

{ "mcpServers": { "autocad": { "type": "http", "url": "http://localhost:5001/mcp" } } }

Smoke test without a client. The response must contain "name":"autodesk-autocad-mcp-server":

Invoke-WebRequest http://localhost:5001/mcp -Method Post -ContentType application/json `
  -Headers @{Accept='application/json, text/event-stream'} `
  -Body '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"probe","version":"1"}}}'

Troubleshooting

Keywords: AutoCAD 2027 MCP, Model Context Protocol, acmcp.dll, MCPHTTPSTART, MCPCONFIG, ACMCP_TOOLS_CONFIG_FILE, ModelContextProtocol.AspNetCore FileNotFoundException, Claude Code AutoCAD.