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

A developer documented three fixes needed to make the MCP server bundled with AutoCAD 2027 (build 26.0.460.2523) work with AI agent clients such as Claude and Cursor. The server fails out of the box because ModelContextProtocol.AspNetCore.dll is missing from the plugin folder, the HTTP server is disabled by default, and the plugin is not loaded at startup, leaving MCPCONFIG and MCPHTTPSTART unrecognized until NETLOAD is run. After copying the matching NuGet package DLL into the plugin's Contents folder and setting the ACMCP_TOOLS_CONFIG_FILE environment variable with a nested toolsConfiguration file enabling the HTTP server, the server listens on http://localhost:5001/mcp over Streamable HTTP.

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. - 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:<port /mcp , the first free port in a range usually 5001 . - Server name autodesk-autocad-mcp-server . Tools include queryAutoCADObjects , discoverAutoCADTypes , aggregateAutoCADObjects , checkAutoCADObjects , manipulateDrawingCanvas . 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 https://www.nuget.org/packages/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 "<path " .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. 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. 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. php 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 . 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"}}}' | Symptom | Cause | Fix | |---|---|---| | MCPCONFIG: The term ... is not recognized | Typed in PowerShell | Type it in the AutoCAD command line | | Unknown command "MCPCONFIG" | Plugin not loaded | NETLOAD acmcp.dll step 3 | | NETLOAD succeeds silently but commands are still unknown | AutoCAD already loaded the DLL itself built-in assistant without registering commands | Restart AutoCAD and NETLOAD right away | | FileNotFoundException ... ModelContextProtocol.AspNetCore | Missing DLL | Step 1 | | MCPHTTPSTART prints nothing, no port opens | enableHttpServer is false | Step 2, then MCPCONFIG → Load | | Load succeeded but Show still says false | Flat or PascalCase JSON | Use the format from step 2 | | getenv "ACMCP TOOLS CONFIG FILE" returns nil | AutoCAD was started before setx | Restart AutoCAD | | COM: Documents.Count = 0 , ActiveDocument is null | Only the Start tab is open | Documents.Add , wait 2–3 s | | COM: RPC E CALL REJECTED | AutoCAD is busy or waiting at a prompt | Retry; cancel the stuck prompt with Esc | | SendKeys types Cyrillic letters | Non-English keyboard layout | Use COM SendCommand instead | | Command line not visible | Hidden | Ctrl+9 | | Error returns after an AutoCAD update | DLL removed or SDK version changed | Repeat step 1 with the new version | Keywords: AutoCAD 2027 MCP, Model Context Protocol, acmcp.dll, MCPHTTPSTART, MCPCONFIG, ACMCP TOOLS CONFIG FILE, ModelContextProtocol.AspNetCore FileNotFoundException, Claude Code AutoCAD.