ShapeItUp

Scripted CAD for AI agents and humans — write TypeScript, get CAD.

ShapeItUp is an MCP server that turns Replicad / OpenCascade into AI-agent-grade CAD tooling. It writes, renders, verifies, and exports parametric 3D models from TypeScript .shape.ts files, headlessly — from the terminal, from Claude Code / Cursor / Claude Desktop / Mistral Vibe, or from CI. A VSCode extension is available as an optional interactive viewer for humans who want to watch the renders happen live.

Install for Claude Code

claude mcp add shapeitup -- npx -y @shapeitup/mcp-server

That's it. claude mcp add registers the server in your Claude Code config so agent sessions pick it up automatically. See the Claude Code MCP docs for scoping options (-s user for all projects, -s project for just this repo).

Install for Cursor / Claude Desktop / other MCP clients

The generic MCP-config snippet:

{
  "mcpServers": {
    "shapeitup": {
      "command": "npx",
      "args": ["-y", "@shapeitup/mcp-server"]
    }
  }
}

Where to put it:

• Cursor — ~/.cursor/mcp.json, or Settings → MCP → Add new server to drop it in through the UI.
• Claude Desktop — ~/Library/Application Support/Claude/claude_desktop_config.json on macOS, %APPDATA%\Claude\claude_desktop_config.json on Windows. Restart the app after editing.
• Mistral Vibe — TOML rather than JSON; see below.
• Any stdio MCP client — hand it npx -y @shapeitup/mcp-server as the server command.

Mistral Vibe

Append to ~/.vibe/config.toml, then run /reload in Vibe:

[[mcp_servers]]
name = "shapeitup"
transport = "stdio"
command = "npx"
args = ["-y", "@shapeitup/mcp-server"]
startup_timeout_sec = 60

Keep startup_timeout_sec: Vibe's default of 10 s is shorter than the first npx download. For the Replicad API reference, save skills/shapeitup/SKILL.md as ~/.vibe/skills/shapeitup/SKILL.md. More options, including vibe mcp add, are in the MCP server README.

Node 20+ required. No native build step; everything ships as WASM.

What you get

A CAD toolkit agents can drive end to end:

• Authoring — create_shape, modify_shape, read_shape, list_shapes, setup_shape_project
• Rendering — render_preview, preview_shape, get_preview (SVG-first, resvg-backed PNGs), open_viewer / close_viewer (interactive browser viewer)
• Verification — verify_shape, check_collisions, check_stack, sweep_check, run_simulation, describe_geometry, validate_joints
• Iteration — tune_params (slider overrides), set_render_mode, toggle_dimensions
• Export — export_shape (STEP / STL / 3MF)
• stdlib — holes, screws / bolts / washers / inserts, bearings, extrusions, patterns, threads, joints + assemble, printHints, and more — all importable from "shapeitup" inside any .shape.ts

29 MCP tools in all — the above plus helpers such as validate_syntax, preview_finder, get_api_reference and open_shape — covering the create → preview → verify → tune → export loop.

Quick example

Prompt to the agent: "I want a mounting bracket, 60×40×4 mm, four M3 through-holes in the corners." The agent calls create_shape and writes:

// bracket.shape.ts
import { drawRoundedRectangle } from "replicad";
import { holes, patterns } from "shapeitup";

export const params = { width: 60, depth: 40, thickness: 4, holeInset: 6 };

export default function main({ width, depth, thickness, holeInset }: typeof params) {
  const plate = drawRoundedRectangle(width, depth, 3)
    .sketchOnPlane("XY")
    .extrude(thickness);

  // holes.through() returns a cutter whose opening sits at Z=0 and drills -Z;
  // lift it to the top face, then cut one at each corner of a 2×2 grid.
  return patterns.cutAt(
    plate,
    () => holes.through("M3", { depth: thickness + 2 }).translate(0, 0, thickness),
    patterns.grid(2, 2, width - 2 * holeInset, depth - 2 * holeInset),
  );
}

Then it calls render_preview and gets back a PNG it can inspect, plus bounding-box + volume metadata to sanity-check against the spec. If the user wants the holes bigger, the agent calls tune_params — no file rewrite needed.

Running in CI / containers

npx -y @shapeitup/mcp-server works anywhere Node 20 runs — Docker, GitHub Actions, GitLab CI. Renders go through @resvg/resvg-wasm; no GPU, no headless Chromium, no native graphics stack required. A cold boot on a stock Node image typically takes ~3 s for the first render (OCCT WASM compile) and < 200 ms thereafter.

VSCode extension (optional)

There is a VSCode extension that subscribes to the MCP server's event bus and shows a live Three.js viewer in the side panel — useful when you want to watch an agent work, or to drive ShapeItUp interactively. Install it from the VS Code marketplace (search for "ShapeItUp") or build from source (see Development).

The extension is entirely optional: the MCP server is headless on its own, does not require VSCode to be running, and produces the same renders whether or not a viewer is attached.

Development

git clone https://github.com/asbis/ShapeItUp.git
cd ShapeItUp
pnpm install
pnpm build          # builds extension, viewer, worker, and mcp-server
pnpm dev            # watch mode
pnpm lint           # tsc -b across packages

Then press F5 in VS Code to launch the Extension Development Host if you want to iterate on the viewer.

Project layout:

packages/
  mcp-server/   -- standalone MCP server (this is the npm package)
  core/         -- Replicad wrappers, stdlib, execution engine (bundled into mcp-server)
  shared/       -- cross-package types (bundled into mcp-server)
  extension/    -- VSCode extension (optional viewer)
  viewer/       -- Three.js viewer surface for the extension
  worker/       -- OCCT WASM web-worker for the extension viewer

See CONTRIBUTING.md for contribution guidelines.

License

MIT