CAD generation, inspection, and validation Agent Skill

Create, modify, inspect, and validate STEP-first parametric CAD parts and assemblies.

Context cost
17.2k tokensestimated from the bundle, loaded when it triggers
Bundle
25 files · 1101.8 kB11 scripts among them — read before you run
Licence
MITthe author’s own terms
Last change
—no release on file
Servers it uses
Noneruns standalone

What it does

Create, modify, inspect, and validate STEP-first parametric CAD parts and assemblies. Use for natural-language CAD specs, reference images, 2D technical drawings, STEP/STP generation or direct inspection, Python CAD source, source-level joints, selector references, geometry facts, measurements, mating deltas, snapshots, and secondary STL/3MF/native GLB outputs from CAD geometry.

What this skill changes about the agent has not been set out here as a list. Its SKILL.md, shown below, says it in the author’s own words.

design
Filed under

Design & Media

The skill itself

A skill is instructions the model reads, so you can see what you are getting: below is the start of its SKILL.md. The front matter loads with every session, the body loads when the skill triggers, and the whole file comes with the install.

SKILL.md10.5 kB · preview
--- name: cad ---
6# CAD generation, inspection, and validation
7
8Provenance: maintained in [earthtojake/text-to-cad](https://github.com/earthtojake/text-to-cad).
9Use the installed local skill files as the runtime source of truth; the
10repository link is only for provenance and release review.
11
12## Purpose
13
14Create or modify parametric CAD models from natural-language requirements, generate validated STEP/STP artifacts, inspect geometry references, and return checked outputs. Treat STEP as the primary CAD artifact. Treat STL, 3MF, and native GLB as secondary export workflows that branch from a STEP-first process. For assemblies, prefer cadpy.assembly.AssemblyHelper with source-level build123d joints, named mating datums, and native labels when the parts have functional assembly relationships.
15
16There are two ways into the STEP workflow: generate from build123d Python source (the default when designing from scratch or modifying a generated model), or import an existing STEP/STP file directly (when no generator exists or the user explicitly targets the STEP file). Both produce the same inspectable artifacts.
17
18## Use this skill when
19
20Use this skill when the user asks for CAD files, STEP/STP files, build123d source, selector refs such as #o1.2.f1, mechanical parts, assemblies, enclosures, brackets, fixtures, holes, counterbores, countersinks, slots, pockets, bosses, standoffs, ribs, fillets, chamfers, shells, source-level joints, mating, or measurements. Also use it when the user supplies reference images or 2D technical drawings of a part to reproduce or take design intent from.
21
22Also use it when the user asks for STL, 3MF, or native GLB output from CAD geometry. Keep those workflows secondary and load supported-exports.md for details. For 2D DXF drawings, use the $dxf skill; when a DXF projects from a 3D part, this skill owns the STEP geometry and $dxf owns the drawing.
23
24Do not use this skill for render-only concept art, CAM toolpaths, engineering certification, FEA conclusions, architectural BIM, or freehand illustration unless the user also needs CAD geometry.
This is a preview of SKILL.md. Download or install the skill to get the whole thing.
In the file
SKILL.md1,420 words
Files25
LicenceMIT
Why you can read it

Nothing in a skill executes. The client loads the text and the model follows it, so a skill can be audited the way a runbook is — by reading it.

What it costs in context

Skills are not billed by the call. They are paid for in context: every token the instructions occupy is a token your code, your diff and your conversation cannot use. Here is what this one takes and when it takes it.

≈100
always loaded
The name and description, so the model knows the skill exists and when to reach for it.
17,075
on trigger
The instruction body and 24 supporting files, read only when the skill fires.
8.6%
of a 200k window
Ten skills this size would take about 86% of the window before you open a file.
050k100k150k200k context window

17.2k tokens, estimated from the bundle at four bytes to the token, held for the rest of the session once it triggers. Heavy. Teams tend to install this one per project rather than globally, and load it only when the job comes up.

Servers bill, skills cost

A server charges by the month. A skill charges once per session, in context, and then keeps charging it for as long as the session lives.

Before and after

The same question, put to the same model twice: once as it comes, and once with these instructions loaded.

No worked example has been published for this skill yet.

The procedure it runs

The procedure has not been set out here step by step. It is in the body of its SKILL.md: the start of it is shown above, and the whole file comes with the install.

Prose, not code

These steps are written for a model to follow, not executed by a runtime. It can still be told to skip one, and it will say so when it does.

Servers it uses

None. This skill calls no MCP servers at all.

Everything it needs is in the instructions, so it works in a project with nothing connected — the model reads the file and changes how it works with what it can already reach.

Its SKILL.md does not declare which tools it asks the agent for, so what it touches is whatever the instructions themselves ask for — read them before you install it.

What it asks for
Writes filesnot declared
Network accessnot declared

This SKILL.md carries no allowed-tools line, so neither is declared. A skill grants no permissions of its own — it can only ask for tools your client already has.

What it will not do

Every skill is narrow, and the useful ones say where they stop. These are the jobs this one is the wrong tool for.

What this skill is not for has not been published here. Nothing is implied by that: it is a section the author has not filled in.

What is in the bundle

25 files, 1101.8 kB on disk. Mostly text — the instructions the model reads — with 11 scripts in it that your client would run only if the instructions tell it to.

  • SKILL.md10.5 kB
  • LICENSE1.1 kB
  • requirements.txt0.1 kB
  • agents/openai.yaml0.3 kB
  • references/build123d-modeling.md8.0 kB
  • references/cad-brief.md6.6 kB
  • references/inspection-and-validation.md5.0 kB
  • references/parameters.md8.7 kB
  • references/positioning.md12.0 kB
  • references/repair-loop.md4.8 kB
  • references/snapshot-review.md5.9 kB
  • references/step-generation.md2.8 kB
  • references/supported-exports.md2.5 kB
  • scripts/inspect/__main__.py0.3 kB
  • scripts/inspect/cli.py0.3 kB
  • scripts/snapshot/__init__.py0.1 kB
  • scripts/snapshot/__main__.py49.6 kB
  • scripts/step/__init__.py0.1 kB
  • scripts/step/__main__.py0.3 kB
  • scripts/step/cli.py4.4 kB
  • scripts/inspect/inspect_refs/__init__.py0.1 kB
  • scripts/inspect/inspect_refs/cli.py24.6 kB
  • scripts/inspect/inspect_refs/inspect.py37.5 kB
  • scripts/snapshot/runtime/render.html0.4 kB
  • scripts/snapshot/runtime/snapshot-render.js915.8 kB
What is not in it

A skill installs nothing and depends on nothing: it is a folder your client reads. This one carries 11 scripts beside the text, so the bundle is 25 files you can review in full before installing. The MIT licence covers the templates and examples as well as the instructions.

Install

Installing copies the bundle into your project. Nothing runs at install time — the files sit on disk until the model reads them.

# CAD generation, inspection, and validation · 17.2k tokens when loaded · macOS, Linux mkdir -p .claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/karanmrn-cad-generation-inspection-and-validation/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/cad-generation-inspection-and-validation" ] && { [ ! -e .claude/skills/cad-generation-inspection-and-validation ] || { mv .claude/skills/cad-generation-inspection-and-validation "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/cad-generation-inspection-and-validation" .claude/skills/ && echo "Installed .claude/skills/cad-generation-inspection-and-validation"
On Windows, or any OS with Node 20+
npx mcprush@latest skill add karanmrn/cad-generation-inspection-and-validation

Windows PowerShell says 'running scripts is disabled on this system'? Run Set-ExecutionPolicy -Scope CurrentUser RemoteSigned once, or type npx.cmd instead of npx (codex.cmd, gemini.cmd, grok.cmd likewise). PowerShell 7 needs neither. Writes to .claude/skills/cad-generation-inspection-and-validation/ in the current project. For every project instead, run mkdir -p ~/.claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/karanmrn-cad-generation-inspection-and-validation/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/cad-generation-inspection-and-validation" ] && { [ ! -e ~/.claude/skills/cad-generation-inspection-and-validation ] || { mv ~/.claude/skills/cad-generation-inspection-and-validation "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/cad-generation-inspection-and-validation" ~/.claude/skills/ && echo "Installed ~/.claude/skills/cad-generation-inspection-and-validation" (macOS, Linux) — or add --global to the npx line. The curl line replaces .claude/skills/cad-generation-inspection-and-validation/ only after the download succeeds, so files left there by another skill of the same name, or by an older release, do not mix in. A copy already there is moved aside, not deleted, and the line prints where. It appears as cad in Gemini CLI, Codex, Copilot and Grok (its own name); Claude Code lists it by the folder name, cad-generation-inspection-and-validation.

Which clients pick it up on their own

A skill is a folder of text. Most of these read a skills folder and pick it up without being told; the rest take the same folder another way — an upload in the app, a parameter on an API call — and then choose it by its description just the same.

Claude Code.claude/skills/
Claude DesktopCustomize › Skills
ChatGPTSkills › Create › Upload
Cursor.cursor/skills/
VS Code.github/skills/
Codex CLI.agents/skills/
Gemini CLI.gemini/skills/
Grok Build.grok/skills/
Microsoft CopilotSkills › Upload a skill
PerplexityComputer › Skills › Upload a skill
DeepSeek Harness.dsh/skills/
Zed.agents/skills/
Devin Desktop.devin/skills/
Windsurf (legacy).windsurf/skills/
OpenAI Agents SDKInstructions or sandbox Skills
HTTP / APIa request parameter
This release
Versionnot versioned
Publishedno release date on file
PriceFree
Referencekaranmrn/cad-generation-inspection-and-validation

Versions

Its author publishes no version number, so there is nothing here to pin to: what you install is the folder as it stands today. Instructions change more often than APIs do — a skill can be rewritten entirely without anything it depends on moving.

Pinning

Nothing to pin to: this skill carries no version number of its own. What you install is what the folder holds on the day you install it.

Reviews

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