Bimwright DWG

dwg-mcp

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Drawing Translation Should Not Stop At Manual Copy-Paste

Construction and engineering drawings carry dense technical text — specifications, notes, dimensions, material callouts, legends. When those drawings arrive in a foreign language, translation is not optional. It is required before the project team can act.

The usual workflow is painful: select text one entity at a time, copy to a translator, paste back, fix the font (because SHX fonts cannot render Vietnamese or CJK), adjust the height, hope nothing shifted. Multiply by hundreds of text fragments per sheet, dozens of sheets per project.

dwg-mcp exists to compress that loop into two steps: select the text, let the AI agent read, translate, and rewrite it in place — with correct font, correct height, correct spatial grouping, and a single undo.

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What dwg-mcp Is

dwg-mcp is a local MCP gateway for Autodesk AutoCAD 2022-2027 DWG workflows.

It has two parts:

• Bimwright.Dwg.Server: a .NET 8 MCP server launched by Claude Code, Cursor, OpenCode, or another stdio MCP client.
• Bimwright.Dwg.Plugin: version-specific AutoCAD add-in shells loaded inside AutoCAD, executing commands against the drawing database.

The agent talks MCP. The server talks to the plugin over a local wire: TCP NDJSON for AutoCAD 2022–2024, and a Named Pipe (loopback, avoids the firewall prompt) for 2025–2027. The plugin talks to the AutoCAD .NET API.

Everything stays on your machine.

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Why It Matters

AI agents make it possible to describe "translate all selected text to Vietnamese" and have it happen — correctly — in the drawing. But intent alone is not enough. AutoCAD text operations require understanding spatial layout, fragment grouping, font limitations, MText vs DBText, block references, and height scaling.

dwg-mcp handles that complexity:

• Spatial clustering groups fragmented text into logical sentences (by block, row, column, paragraph).
• Automatic font handling creates a Unicode-capable text style and applies it — no more SHX question marks.
• Height scaling compensates for the different visual density of Latin vs CJK text.
• MText conversion upgrades single-line fragments into multi-line text when safe.
• Single undo wraps each operation in a transaction.

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Usage Evidence

220 completed tool calls over 19 days of active use on production construction drawings. 98.2% success rate.

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Architecture

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| AI Client | | Claude / Cursor / OpenCode| +---------------------------+ | | stdio MCP v +---------------------------+ | Bimwright.Dwg.Server | | .NET 8 / C# | +---------------------------+ | | TCP NDJSON (2022-2024) / Named Pipe (2025-2027) | token auth v +---------------------------+ | Bimwright.Dwg.Plugin | | AutoCAD 2022-2027 shells | +---------------------------+ | | LockDocument() v +---------------------------+ | AutoCAD .NET API | | ObjectARX 2022-2027 | +---------------------------+

See ARCHITECTURE.md for threading, discovery, and auth details.

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Install

Download the client setup ZIP from GitHub Releases. It includes a self-contained MCP server and release-specific AutoCAD plugins. Check packedAutocadYears in the downloaded ZIP's manifest.json and its bundle PackageContents.xml for the included years; check the release notes for years verified in a running AutoCAD host. Source shells cover 2022–2027, while packaged plugins and tested host years depend on the release. For a year absent from the package, build the plugin from source with that year's AutoCAD SDK.

$tag = (Invoke-RestMethod https://api.github.com/repos/bimwright/dwg-mcp/releases/latest).tag_name

$zip = "$env:TEMP\DwgMcp.Setup-$tag-win-x64.zip" $dir = "$env:TEMP\DwgMcp.Setup-$tag-win-x64" Invoke-WebRequest "https://github.com/bimwright/dwg-mcp/releases/download/$tag/DwgMcp.Setup-$tag-win-x64.zip" -OutFile $zip Invoke-WebRequest "https://github.com/bimwright/dwg-mcp/releases/download/$tag/DwgMcp.Setup-$tag-win-x64.zip.sha256" -OutFile "$zip.sha256" $expected = ((Get-Content "$zip.sha256" -Raw).Trim() -split '\s+')[0] if ($expected -notmatch '^[a-fA-F0-9]{64}$' -or (Get-FileHash $zip -Algorithm SHA256).Hash -ne $expected) { throw 'Setup ZIP checksum mismatch' } if (Test-Path -LiteralPath $dir) { throw 'Use a fresh extraction directory; existing files were preserved.' } Expand-Archive $zip -DestinationPath $dir

Choose an included/installed year; use the exact health tag for an update.

powershell -ExecutionPolicy Bypass -File "$dir\install.ps1" -WhatIf -Years 2024 -Client none -SetupZip $zip -ReleaseTag $tag powershell -ExecutionPolicy Bypass -File "$dir\install.ps1" -Years 2024 -Client none -SetupZip $zip -ReleaseTag $tag

The installer:

• detects installed AutoCAD years (a year counts when its acad.exe exists) and installs every packed year that matches; -Years 2024,2027 forces an explicit list;
• requires AutoCAD to be closed; caught errors trigger hash-verified recovery of recorded server/plugin/client-config replacements, with retained backup paths reported if restoration is incomplete;
• deploys %APPDATA%\Autodesk\ApplicationPlugins\Bimwright.Dwg.bundle\ (removing stale bundles with the same ProductCode) and the server at the fixed path %LOCALAPPDATA%\Bimwright\dwg-mcp\server\current\dwg-mcp.exe;
• seeds %LOCALAPPDATA%\Bimwright\dwg-mcp\dwgmcp.config.json with "toolsets": ["all"] on a fresh install — an existing toolsets key is kept;
• wires clients selected by -Client (none skips edits; omission still selects detected clients). Use an explicit scope in both preview/apply. Routes without a verified CLI recovery path, currently Grok, stop before replacement. Config edits keep JSONC comments; existing .bak files are preserved and a unique backup is created instead. Existing Codex entries receive command-only repoints so args/env/other TOML tables survive. The entry name is dwg-mcp.

Restart AutoCAD, then restart wired MCP clients to load dwg-mcp.

Updating: keep the exact reviewed release tag, verify its ZIP/sidecar and complete extracted manifest, then preview/apply the same explicit year/client scope. Close AutoCAD and affected clients first. The server path stays server\current\. The installer preserves settings, ToolBaker data and captures. Ambiguous legacy/current roots stop without merging; a committed DWG migration marker permits retaining both separately. Recovery covers caught errors; process crashes/power loss and actual client reconnect still require separate verification. Uninstall is not upgrade rollback.

Uninstall: uninstall.ps1 removes the bundle, the server copies, discovery files and caches under %LOCALAPPDATA%\Bimwright\dwg-mcp\ (settings, config, logs and captures are kept; -Purge removes those too). Client config entries are never touched — remove the dwg-mcp entry yourself, or run install.ps1 -Uninstall -Client first.

NuGet (gateway only): dotnet tool install --global Bimwright.Dwg.Server --version 2.1.2 installs the framework-dependent gateway and requires .NET 8. Install the matching AutoCAD plugins from the Setup ZIP separately; the NuGet package does not install plugins.

Claude Desktop: download dwg-mcp-desktop-2.1.2.mcpb and its checksum from the same release, then install it through Settings → Extensions → Advanced settings. It launches the exact gateway executable supplied by the 2.1.2 Setup ZIP; it does not install the gateway or plugins and does not fall back to a NuGet/PATH copy. An executable override must have the same SHA-256.

Developer (local SDK): dotnet build the year you have, then pwsh scripts/install.ps1 -Years 2024 from the repo (copies that year’s bin output). NETLOAD remains available for Debug DLLs.

3. Wire up your MCP client

Check the selected clients' Client : summary lines. The example above uses -Client none, so wiring remains a separate step: preview/apply the intended client selection or wire by hand in that client's supported config (e.g., .mcp.json):

{

"mcpServers": { "dwg-mcp": { "command": "C:\\Users\\ \\AppData\\Local\\Bimwright\\dwg-mcp\\server\\current\\dwg-mcp.exe", "args": [] } } }

Select an initial AutoCAD instance by PID (or an unambiguous 4-digit year):

{

"mcpServers": { "dwg-mcp": { "command": "C:\\Users\\ \\AppData\\Local\\Bimwright\\dwg-mcp\\server\\current\\dwg-mcp.exe", "args": ["--target", "pid:12345"] } } }

Before writes, call dwg_list_available_targets and dwg_switch_target(target="pid: "). The default verify=true authenticates the selected process and confirms the active drawing; verify=false permits reads only. --target controls initial selection and does not authorize writes. A year or automatic selection matching multiple instances returns AMBIGUOUS_TARGET.

Once bound, changing instances requires pid: or id:acad- - ; leaving a live confirmed target also requires rebind=true. Reselecting the same process with verify=false removes write confirmation. It retains the previous expected drawing lifetime ID unless rebind=true resets it or an explicit expected_document_id replaces it. After opening or switching drawings, inspect dwg_health().target; confirming a different drawing requires its matching expected_document_id or rebind=true. Failed verification preserves the previous binding, and pending calls under an older binding are refused before sending. Update gateway and plugin together: legacy plugins cannot be verified for writes, and new plugins refuse unguarded writes from old gateways.

With --read-only, dwg_switch_target is unavailable and direct calls are refused. Start the gateway with --read-only --target pid: (or --target id:acad- - ), then check health and the current target. On TARGET_LOST or TARGET_CHANGED, call dwg_list_available_targets and restart the gateway with the intended explicit --target. A lost binding never selects another instance automatically.

Use --read-only to strip write-capable toolsets (query/view/meta routing remain as configured). Use --toolsets all or an explicit list that includes the defaults you need (a custom list replaces the default set — e.g. query,modify,meta,view,annotation). Env: BIMWRIGHT_DWG_TOOLSETS=….

dwg_send_code is available by default via meta. Use --enable-send-code / --disable-send-code (JSON enableSendCode; e