dsh-sw-cad

dsh-sw-cad

Two MCP servers and two skills that let a DeepSeek Harness or Codex agent drive real CAD software. They wire up two existing open-source projects — U-C4N/Autocad-MCP and wzyn20051216/solidworks-automation-skill — so an agent can draw in AutoCAD, model in SolidWorks, and export the results. This repository is the configuration layer: isolated environments, launch parameters, on-demand loading and client registration. It does not fork, patch or repackage either server. Where upstream lacks a capability — SolidWorks has no way to hide its 66-tool catalog — this repository adds a small shim in front of it instead of touching it.

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What it does, and when you want it

A CLI agent that can read a drawing is useful. One that can produce one is a different tool. With this kit installed, dsh or Codex can take a sentence like "draw an M6 threaded-hole bracket on an ISO A3 sheet and export PDF" and actually do it — create layers, draw geometry, dimension it, stamp a title block, run a validator, and hand back a file.

The catch is the same as every COM automation: the CAD application must be running, and the agent must run as the same Windows user and integrity level as the CAD app. This is not a cloud service and there is no headless substitute for native .dwg / .sldprt output.

Two skills are the entry points. They load lazily — the SKILL.md is read only when a request matches its description, so an idle session pays nothing for them:

Skill	How it works
solidworks-automation	Script-driven: 66 Python modules (30 sw_*.py COM wrappers plus OCCT/FEA/DFM tooling), with preflight, capability gating and evidence chains
autocad-mcp-pro	Authored here (upstream ships no AutoCAD skill). Drives the AutoCAD MCP through its two meta-tools

Two MCP servers are the muscle, registered in the client config:

Server	Tools advertised	Idle cost	Mode
autocad	2	365 tokens	Upstream DISCOVERY_MODE=search: only search_tools + call_tool; the 242-tool catalog is searched by keyword
solidworks	2	256 tokens	mcp-shim/ from this repository in front of upstream's 66-tool server (50 solidworks_* + 14 cadstudio_* + 2 design_*), which would otherwise cost 23,404

Tool schemas are paid for before the first request. Connected directly the two servers cost 107,136 tokens; through this kit they cost 621, a 99.4% cut. Reproduce with mcp-shim/verify_shim.py.

you speak natural language
   │
   ├─ dsh / Codex lazily loads a skill by its SKILL.md description
   │      ├─ solidworks-automation  → sw_*.py scripts → COM → SolidWorks
   │      └─ autocad-mcp-pro        → search_tools / call_tool → MCP → AutoCAD
   │
   └─ MCP servers (cordis.patch.yml / codex config.toml)
          ├─ autocad    upstream discovery mode, 242 tools on demand
          └─ solidworks our shim, 2 meta-tools, 66 tools on demand
                          └─ spawns upstream server.py lazily

What is upstream, what is ours

This matters more than usual here, because the two servers are other people's work. The split is:

Part	Origin	License
AutoCAD MCP server (autocad-mcp-pro)	U-C4N/Autocad-MCP, installed from PyPI	MIT
SolidWorks skill + MCP server	wzyn20051216/solidworks-automation-skill, cloned at install time	MIT
skills/autocad-mcp-pro/SKILL.md	Authored here — upstream has no AutoCAD skill	MIT
mcp-shim/ (SolidWorks discovery shim + lexicon)	Authored here — upstream has no equivalent	MIT
bin/, lib/ (including probe.py, which checks for the CAD COM servers), package.json, cordis.patch.yml, install.ps1, bootstrap.ps1, codex-config.snippet.toml, assets/, READMEs	Authored here	MIT

Nothing upstream is vendored. The installer fetches the PyPI package and clones (or zip-downloads) the SolidWorks repository at install time, so you always get upstream's current code and upstream keeps ownership of it. The value this repository adds is the part that was missing: verified launch parameters, the discovery-mode configuration, a discovery shim for the server that lacks one, the on-demand skill wiring, the junction trick that keeps gigabytes off C:, and an installer that survives a blocked git protocol.

Install

Three ways in. Pick one, then check the prerequisites at the end of this section.

1. As a dsh plugin (recommended)

dsh plugin --profile web add dsh-sw-cad

That is the whole install. package.json declares dsh.bundle.patch, so dsh picks up this repository's cordis.patch.yml, which inserts one row: this package. The package is a real cordis plugin (lib/index.js), not a wrapper around a binary, so dsh imports it from the profile and nothing has to be on PATH.

On first load the plugin resolves its own paths, installs the pinned upstream servers if they are missing (a few minutes, once), and then registers the two MCP clients with absolute paths. If the install cannot succeed it throws with the failing path and the command to re-run, instead of registering rows that would fail silently. SW_CAD_NO_AUTO_INSTALL=1 turns the automatic install off and surfaces the missing pieces as an error instead.

2. npm, global (adds the CLI)

npm install -g dsh-sw-cad
dsh-sw-cad install

Same result, plus dsh-sw-cad on PATH for doctor, where and serve — useful when you want to check the install without booting dsh.

3. Without npm: bootstrap.ps1

git clone https://github.com/27painter/dsh-sw-cad.git
cd dsh-sw-cad
.\bootstrap.ps1 -Check     # report only, changes nothing; exits 1 if something is missing
.\bootstrap.ps1            # install whatever is missing

It inspects ten things and repairs only what is absent or stale:

Check	Fixed by
Python ≥ 3.11	nothing — it reports the problem and stops
venv-autocad + autocad-mcp-pro	install.ps1
venv-solidworks + mcp / pymupdf / ezdxf / pywin32	install.ps1
SolidWorks skill clone	install.ps1
discovery shim	copied from this repository
shim catalogue	rebuilt with --build-catalog, also when older than server.py
~/.dsh/skills junction	created
~/.dsh/cordis.patch.yml entries	install.ps1 (backs the file up first)
~/.codex/skills junctions	created
~/.codex/config.toml entries	appended, with a backup

Running it twice is a no-op. It exits 0 when everything is in place and 1 otherwise, so it is safe to wrap in a script or hand to an agent. Nothing is downloaded unless a core piece is actually missing.

[!WARNING] Route 3 also writes ~/.dsh/cordis.patch.yml. If you installed the plugin as well, that is a second registration of the same two servers under the same serverName, and dsh refuses the duplicate — the session fails to start. Use one route or the other, not both: with the plugin installed, keep ~/.dsh/cordis.patch.yml at [].

Commands

Command	What it does
dsh-sw-cad install	install the pinned upstream servers and write ~/.dsh/sw-cad.json
dsh-sw-cad doctor	report present/missing pieces and the pinned versions, change nothing, exit 1 if something is missing
dsh-sw-cad where	print every path the servers will use
dsh-sw-cad serve autocad|solidworks	run one MCP server over stdio, for manual testing

install is idempotent, and the plugin runs it for you on first load. Versions are pinned in lib/upstream.json — autocad-mcp-pro 1.6.0 and one SolidWorks skill commit — so a machine that installs today and one that installs next month get the same servers.

[!TIP] Rather not run any of this yourself? Paste the block below into dsh, Codex, or any agent that can run commands on this machine. It carries everything the agent needs, so you can read the rest of this section only if something goes wrong.

Install https://github.com/27painter/dsh-sw-cad on this Windows machine.

Run: npm install -g dsh-sw-cad && dsh-sw-cad install
That installs the package, then the two upstream servers (AutoCAD MCP and the
SolidWorks skill) plus the client entries. dsh-sw-cad install is idempotent and
only touches what is missing.

Do not run it elevated: it must run as the same Windows user as AutoCAD and
SolidWorks. It writes nothing on C: except ~/.dsh and ~/.codex, and never touches
the CAD installations or the registry.
Then verify with: dsh-sw-cad doctor, dsh --profile headless --dump-config, codex mcp list.
Report any step that fails instead of silently working around it.

Prerequisites

• Windows 10/11 with AutoCAD and/or SolidWorks installed
• Python ≥ 3.11 on PATH (python --version)
• dsh (DeepSeek Harness) or Codex CLI; Node ≥ 20 for routes 1 and 2
• Git — optional; the installer falls back to a codeload zip when git is blocked

What if the CAD applications are not installed

The plugin checks for both COM servers before registering anything (lib/probe.py, a registry ProgID lookup — it does not launch either application). A machine with only AutoCAD registers only the AutoCAD server, and vice versa; a machine with neither registers nothing and says so in the log instead of offering tools that could only fail.

[dsh-sw-cad] solidworks: no COM server registered on this machine, not registering it
[dsh-sw-cad] registered autocad (base D://cad-agents, upstream pinned in lib/upstream.json)

SW_CAD_DISABLE=autocad,solidworks turns that decision into a setting, and dsh-sw-cad doctor prints what the probe found without starting dsh.

Note that installed is not the same as running. AutoCAD registered but closed means the AutoCAD tools wait for the application and then fail with a message about a modal dialog; SolidWorks' own health check reports the install, not the running instance. Starting the CAD application as the same Windows user as your agent is the last step of any install.

Version support

Upstream verifies against a single release but writes for a range. The honest picture:

CAD	Verified	Expected to work	Why
AutoCAD	2026 (every COM path, live run), 2027 (API compatible)	2025 / 2024 / 2023	COM goes through the long-stable ActiveX API. Run the upstream scripts\smoke_*_com.py against your build to confirm. And if COM cannot do something on your version, the ezdxf backend still can — it needs no AutoCAD at all.
SolidWorks	2026 SP4.1 (upstream's acceptance target)	2025 / 2024 / 2023	The code carries explicit SW2024 fixes (Chinese edition: selecting a sketch by name, AddComponent4 returning None), and upstream's contributor guide asks for 2020–2025 compatibility. 2023 has not been exercised.

Older versions are not refused — nothing checks a version number. They are simply outside what upstream verified, so start with one small job and look at the result before trusting a full drawing.

Appendix — upstream's own install steps

These are the upstream projects' own instructions. This is also what install.ps1 automates, so read it if you want to understand or debug the install.

AutoCAD MCP server — upstream install. Into a venv on the data drive (recommended here):

python -m venv D:\cad-agents\venv-autocad
D:\cad-agents\venv-autocad\Scripts\python.exe -m pip install "autocad-mcp-pro[full]"
D:\cad-agents\venv-autocad\Scripts\autocad-mcp.exe --help    # stdio server entry point

Upstream's own one-liners, if you do not want a venv:

pip install autocad-mcp-pro              # or: uvx autocad-mcp-pro
autocad-mcp                              # backend auto-selected
AUTOCAD_MCP_BACKEND=ezdxf autocad-mcp    # headless DXF, no AutoCAD needed
AUTOCAD_MCP_BACKEND=com   autocad-mcp    # live AutoCAD (needs the [com] extra)

Extras: [com] = live AutoCAD control (pywin32 + Pillow), [pdf] = matplotlib for PDF/PNG output, [office] = openpyxl for XLSX takeoffs, [full] = all of them. Upstream also documents an HTTP transport (autocad-mcp --transport http --port 8000) and a JSON config for Claude Desktop / Cursor.

SolidWorks skill + MCP — upstream quick start. Upstream offers three entry points; pick one:

# Option 1 — skill only (simplest)
npx github:wzyn20051216/solidworks-automation-skill

# Option 2 — MCP via Smithery
npm install -g @smithery/cli
smithery mcp add wzyn20051216/solidworks-automation-skill --client codex --config '{}'

# Option 3 — CAD Studio desktop app, from the upstream Releases page

Manual clone (what this kit does, and what you need if you want the skill on the data drive):

git clone --depth 1 https://github.com/wzyn20051216/solidworks-automation-skill.git D:\cad-agents\dsh-skills\solidworks-automation
D:\cad-agents\venv-solidworks\Scripts\python.exe -m pip install -r D:\cad-agents\dsh-skills\solidworks-automation\requirements.txt
D:\cad-agents\venv-solidworks\Scripts\python.exe -m pip install -r D:\cad-agents\dsh-skills\solidworks-automation\mcp-server\requirements.txt
D:\cad-agents\venv-solidworks\Scripts\python.exe D:\cad-agents\dsh-skills\solidworks-automation\scripts\cad_doctor.py

Optionally put the discovery shim in front of SolidWorks (every route above does this for you; these are the manual steps). Without it the client carries all 66 tool schemas — 23,404 tokens — in every request:

New-Item -ItemType Directory -Force -Path D:\cad-agents\mcp-shim | Out-Null
Copy-Item .\mcp-shim\* D:\cad-agents\mcp-shim\ -Force

# build the search catalogue (once, and again after any upstream update)
D:\cad-agents\venv-solidworks\Scripts\python.exe D:\cad-agents\mcp-shim\sw_discovery_shim.py `
  --python D:\cad-agents\venv-solidworks\Scripts\python.exe `
  --server D:\cad-agents\dsh-skills\solidworks-automation\mcp-server\server.py --build-catalog

Register both servers with your client. dsh reads ~/.dsh/cordis.patch.yml — copy this repository's cordis.patch.yml there. It carries no absolute path: each row calls dsh-sw-cad serve <target>, so the only requirement is that the binary is on PATH (npm install -g dsh-sw-cad). Codex reads ~/.codex/config.toml — append codex-config.snippet.toml, or use upstream's own registrar (mcp-server\register_codex_mcp.ps1 -Python <venv python> -InstallDependencies). The Codex snippet does contain absolute paths, so adjust those to your -BaseDir.

Make the skills visible. Both clients only scan their own skills directory:

# dsh: one junction for the whole skills folder (matches what install.ps1 does)
New-Item -ItemType Directory -Force -Path "$env:USERPROFILE\.dsh" | Out-Null
New-Item -ItemType Junction -Path "$env:USERPROFILE\.dsh\skills" -Target "D:\cad-agents\dsh-skills"

# Codex: one junction per skill (its skills folder may hold other skills)
New-Item -ItemType Directory -Force -Path "$env:USERPROFILE\.codex\skills" | Out-Null
New-Item -ItemType Junction -Path "$env:USERPROFILE\.codex\skills\solidworks-automation" -Target "D:\cad-agents\dsh-skills\solidworks-automation"
New-Item -ItemType Junction -Path "$env:USERPROFILE\.codex\skills\autocad-mcp-pro"       -Target "D:\cad-agents\dsh-skills\autocad-mcp-pro"

Appendix — what install.ps1 does

install.ps1 runs everything in the appendix above, plus the parts that are easy to get wrong: both venvs on the data drive, the junctions, the discovery-mode parameters, and a timestamped backup of ~/.dsh/cordis.patch.yml.

powershell -ExecutionPolicy Bypass -File .\install.ps1

# custom locations / force rebuild
.\install.ps1 -BaseDir "E:\cad" -WorkDir "E:\AutoCad" -Force

It checks Python, creates the directories, builds the venvs, installs autocad-mcp-pro[full] and the SolidWorks requirements, clones the skill (or zip-downloads it when git is blocked), installs the discovery shim and builds its catalogue, junctions the skills into ~/.dsh/skills, writes the dsh config, and drops the AutoCAD skill in place.

If you are not sure what is already on the machine, run bootstrap.ps1 instead: it decides whether install.ps1 is needed at all.

Codex users still need one step — append codex-config.snippet.toml to ~/.codex/config.toml and junction the two skills into ~/.codex/skills/ (last four commands of the appendix above).

[!IMPORTANT] Start AutoCAD / SolidWorks first, as the same user. COM automation crosses a process boundary that Windows guards by user and integrity level. An agent started elevated while the CAD app runs normally (or vice versa) will connect to nothing, and the failure looks like "the tool did nothing".

Usage

Just describe the drawing. The skill loads itself.

Open AutoCAD, draw a bearing housing: base 120×80×10, upright 60 high × 12 thick,
φ40 through hole on top. ISO A3 sheet with title block and dimensions, save to
D:\AutoCad and export PDF.

In SolidWorks, build a flange: OD 100, 20 thick, 30 bore, four M10 bolt holes on a
bolt circle. Save as SLDPRT and export STEP.

Practical notes, learned the hard way:

• SolidWorks tools nest their arguments. The upstream tools take their payload under a params key, so a call looks like call_tool(name="solidworks_sketch_and_extrude", arguments={"params": {"shape": "rectangle", "width_mm": 60, "height_mm": 40, "depth_mm": 10}}). AutoCAD tools take theirs flat. Getting this wrong fails with a pydantic message about a missing params field, which is the hint.
• Say one CAD at a time. Mentioning both loads both skills and mixes the task.
• Ask for a plan first on anything complex. Both skills have a planning step; approving a plan before geometry is drawn is cheaper than undoing a bad drawing.
• Ask for the preview. The AutoCAD path ends in an 8-step validator plus a screenshot; the SolidWorks path exports four orthographic previews. "Show me the preview" is a fair request and the skills honor it. One caveat, measured here: the AutoCAD screenshot needs the window to be visible — with AutoCAD hidden or minimised it comes back blank. The geometry itself is always verifiable through the API (handles, bounding boxes, mass properties), so do not treat a blank image as a failed drawing.

Verification

# everything present? read-only, exits 1 if something is missing
dsh-sw-cad doctor

# every path the servers will use
dsh-sw-cad where

# dsh sees both servers and both skills
pnpm dsh --profile headless --dump-config
pnpm dsh --profile headless "list available skills"

# SolidWorks skill self-check (Python deps + COM)
& "D:\cad-agents\venv-solidworks\Scripts\python.exe" "D:\cad-agents\dsh-skills\solidworks-automation\scripts\sw_preflight.py"

# both MCP servers answer a handshake through the same entry point dsh uses
node bin\dsh-sw-cad.mjs serve solidworks     # expects solidworks-discovery, 2 tools
node bin\dsh-sw-cad.mjs serve autocad        # expects AutoCAD MCP Pro, 2 tools

# Codex
codex mcp list

What was verified before publishing, against live applications (AutoCAD 2026 and SolidWorks 2026 running): system_status returns connected: true, backend: com, the running version and the active document name; drawing_info returns the open document's entity count, extents and units; layer_list returns the live layer table; and the SolidWorks side reports status: ok with the running instance detected. Both serve targets also answer a JSON-RPC handshake through the package's own binary — the AutoCAD server reports AutoCAD MCP Pro 3.4.11 (the pip package is 1.6.0, the server carries its own version), the shim reports solidworks-discovery 1.0.0 behind upstream solidworks_mcp 1.30.0 — and each advertises exactly two meta-tools. Discovery finds gear_draw_spur_front_view / keyway_draw_keyed_bore by keyword; dsh --dump-config loads both rows with command: dsh-sw-cad; the SolidWorks preflight passes. The shim was measured end to end on 36 Chinese and English queries: tools/list costs 256 tokens instead of 23,404, every query returned a correct top hit, and call_tool forwarded a live solidworks_health_check to a running SolidWorks 2026.

Design notes

1. Discovery mode is the whole trick. 242 tool schemas cost 83,732 tokens if advertised. In discovery mode the client sees two tools (365 tokens) and searches a catalog that carries 206 AutoCAD command names plus 1439 synonyms — say "chamfer" and it finds FILLET.

2. SolidWorks needed the same trick, so the shim exists. Upstream's server registers all 66 tools unconditionally; measured on the wire that is 23,404 tokens before the first request. The shim advertises search_tools + call_tool (256 tokens), serves search from a cached catalogue, and spawns the real server only when a tool is actually called. The 57 bilingual alias groups in sw_lexicon.json are what make "拉伸凸台" land on solidworks_sketch_and_extrude and "干涉检查" on solidworks_interference_check. Upstream is untouched, so a git pull in the skill directory still works.

3. Keep TOOL_PROFILE=full and TOOL_PACKS=all. They only narrow the searchable catalog and do not change idle cost. Measured: lean + core,mech drops the catalog to 58 tools and makes the parametric gear and keyway tools unfindable. Narrowing packs loses capability without saving a token.

4. Junctions, not copies. dsh only scans ~/.dsh/skills, Codex only scans ~/.codex/skills. Directory junctions point both at the data drive; neither tool notices. Deleting a junction does not delete data.

5. Scope the file access. The AutoCAD server's ALLOWED_PATHS is empty by default, and its own README says to set it. This kit sets it to a working directory.

6. Know what is verified. The version table under Install says it plainly: upstream verified AutoCAD 2026 and SolidWorks 2026 SP4.1. Everything else is expected, not proven — run one small job first.

7. Discovery is not free, it is deferred. Every tool call costs one extra round trip: search, then call. For a single "draw a box" that is slower than calling the upstream tool directly, and the shim's catalogue can go stale if the upstream skill is updated without --build-catalog. It is the right trade when a session makes several calls, which is the normal case for CAD work.

8. It ships as a plugin, not as a bin the patch calls. The first version registered two MCP client rows whose command was dsh-sw-cad, which only resolves when the package is installed globally — so dsh plugin add on its own left two rows that could not start. A reviewer caught that, correctly. lib/index.js now imports as a cordis plugin and registers the two clients itself with absolute paths, which removes the PATH dependency and lets it check the upstream before registering anything.

9. Pinned, because "latest" is not a version. lib/upstream.json records the exact autocad-mcp-pro release and the exact SolidWorks skill commit this bundle was validated against; install.ps1 uses them for both the pip install and the archive download. Bumping them is a deliberate commit, and the shim catalogue has to be rebuilt when you do.

Troubleshooting

Symptom	Cause / fix
dsh lists no skills	~/.dsh/skills must be a junction whose target exists; folder name must equal the frontmatter name
Codex lists no skills	both junctions under ~/.codex/skills\; Codex must support skills
AutoCAD tools return nothing	CAD not running, or different user/integrity level; set AUTOCAD_MCP_BACKEND=com to rule out the ezdxf fallback
SolidWorks preflight fails	missing deps (requirements.txt of the skill) or SW not running
search_tools offers a tool that no longer exists	the shim's catalogue is stale — rerun --build-catalog
call_tool says "Could not start the SolidWorks MCP server"	the --python / --server paths in the client config are wrong, or the skill was moved
codex mcp list empty	the snippet must sit at the end of config.toml; paths need doubled backslashes
git clone fails during install	the installer falls back to a codeload zip automatically

License

MIT (see LICENSE). Upstream components remain under their own MIT licenses; this repository redistributes neither.