classcad-ai

Everything that lets AI agents build and verify CAD models.

Describe a part in plain language. An agent writes a ClassCAD program, runs it live, proves the result, and hands you a model that lives inside any app. Scroll through it: every picture on this page is drawn live, by the same code that renders the film.

classcad-mcp · add it to your agent*

in a terminal

$ claude mcp add classcad --scope user -- npx -y @awv-informatik/classcad-mcp

claude_desktop_config.json

{
  "mcpServers": {
    "classcad": { "command": "npx", "args": ["-y", "@awv-informatik/classcad-mcp"] }
  }
}

~/.codex/config.toml

[mcp_servers.classcad]
command = "npx"
args = ["-y", "@awv-informatik/classcad-mcp"]

.vscode/mcp.json

{
  "servers": {
    "classcad": { "type": "stdio", "command": "npx", "args": ["-y", "@awv-informatik/classcad-mcp"] }
  }
}

~/.cursor/mcp.json

{
  "mcpServers": {
    "classcad": { "command": "npx", "args": ["-y", "@awv-informatik/classcad-mcp"] }
  }
}

opencode.json

{
  "mcp": {
    "classcad": { "type": "local", "command": ["npx", "-y", "@awv-informatik/classcad-mcp"] }
  }
}

* Or just point your agent at this site, and it will install it for you.

starter.buerli.io · with-claude-sprocket

teeth13

strandsduplex

part.updateExpression · live in the page

02 Execute run_script · live session

Loading the model …

01 · Describe

Describe it.

Plain language in. Verified geometry out.

› ↵

Thinking…

docsv1.solid.* · recipes/direct-modeling-eif · recipes/verification
run_scriptwriting the program

02 · Execute

One way to execute.

The agent writes a program. ClassCAD runs it live.

run_scriptlive ClassCAD session

Constrained sketches, dimensions, expressions.

ClassCAD solves the constraints. Dimensions bind to named expressions, so one value drives the whole shape, and the agent knows how to set them up.

It returns the model, not a status.

return

api.tree()

api.graphic()

03 · Verify

Verification is built in.

Proof by numbers and deterministic renders, not status codes.

view: 'iso'
lines: true
section: { origin, normal }
highlightAt + markers
drawing: 'first-angle'

calculateMassProperties()

volume18 338.53mm³✓

cog−0.11 · −0.20 · −0.13✓

extents44.4 × 44.1 × 34.6✓

04 · Embed

Part of any app.

Traditional CAD bolts buttons and dialogs onto its own modeler. ClassCAD is a headless engine: it runs inside your product.

runs as: cross platform C++WebAssembly
API wrappers: JavaScript · Node.jsPython.NET
deploys to: webserverclouddesktopmobile

Change it live.

your app@buerli.io/react

// your app · @buerli.io/react
const { api, Geometry } =
useBuerliCadFacade('with-claude-sprocket')
useEffect(() => {
updateSprocket(api, partId, {
teeth: 13,
strands: 2,
})
})
return (
<Canvas>
<Geometry />
</Canvas>
)

Four branches, one repository.

What knows the API, what runs the program, what proves the result, and where the agent lives. Every package is open on GitHub.

classcad-ai

Knowledge

The Skill

@classcad/skill

every method of the API, verified, and its recipes

Discovery

@classcad/skill/discovery

search, describe, and the docs tool

Execution

The Script

@classcad/script

one way to execute: a program, run_script

The Engine

classcad-cli · wasm

ClassCAD itself, on a worker or in the page

classcad-cli

worker · ws://localhost:9094

on your machine, in Docker, or hosted

download

ClassCAD WASM

in the browser, or inside the MCP

the same engine, no server

Proof

The Renderer

@classcad/renderer

views, drawings, sections and diffs

The Numbers

the engine

mass properties and geometry probes

Hosts

The MCP Server

@awv-informatik/classcad-mcp

Claude Code, Codex, OpenCode, Cursor, VS Code

The In-App Agent

@buerli.io/ai

a chat panel in buerli apps

Knowledge · @classcad/skill

The knowledge.

The ClassCAD API, whole: 264 methods, each documented and verified against a live engine, and the recipes that combine them into parts and assemblies. One search serves it all: BM25-ranked, camelCase split, plurals folded, and fluent in CAD.

Seen in 01 Describe: the agent reads the docs ↑

Methods, by domain

part76
assembly63
sketch50
common22
curve21
solid21
drawing2d11

In all264

Recipes

One search

holeis abore

roundis afillet

Execution · @classcad/script

The medium.

An agent never dictates one call per turn. It writes a program, with variables, loops and geometry filtered by plain arithmetic, against api.v1, api.tree() and api.graphic(), and runs it through run_script: the same in the browser, in the MCP and in Node.

browser · @buerli.io/aiMCP · classcad-mcpNode · runScript

Seen in 02 Execute: the sprocket's program ↑

a scriptrun_script

const { result: part } =
await api.v1.part.create({ name: 'Plate' })
await api.v1.part.box({
id: part, length: 80, width: 50, height: 10 })
const { result: { volume } } = await api.v1
.part.calculateMassProperties({ id: part })
return { part, volume }

returns{ part: 4, volume: 40000 }

and runs it@classcad/script/node

import { connectSession, runScript } from '@classcad/script/node'
const session = await connectSession() // a classcad-cli worker, :9094
const res = await runScript(script, session)
// res → { ok: true, returned: { part: 4, volume: 40000 } }

Proof · @classcad/renderer

The eyes.

Images of the live model, the same every time: no GPU, no camera state. Named views and turntable cameras; technical drawings in either projection, hidden edges dashed; sections capped and hatched; highlights, probe markers and pixel diffs.

iso viewslineshidden edgessectionsx-raydrawingsmarkerspixel diffs

Seen in 03 Verify: iso, lines, section, markers, drawing ↑

The two methods

First-angleISO E · Europe

Third-angleISO A · the Americas

Hosts · @awv-informatik/classcad-mcp · @buerli.io/ai

The envoys.

Two envoys make the part: the MCP server, which serves any agent host and joins any ClassCAD app, or works on its own; and the assistant, which lives inside the app, with any tool-calling LLM.

Seen in 04 Embed: the part inside an app ↑

Any MCP host

Claude Code
Codex
OpenCode
Claude Desktop
VS Code
Cursor

mcpone daemon
per machine

On its owna worker, or its own WASM
Joins any ClassCAD appby invite

The in-app assistant

Make a flanged bushing.

Done: a 60 mm flange with a flat, a 30 mm hub, bolt holes and a port.

your ClassCAD app