agentcad
Open-source MCP server for AI agents to design 3D parts
A razor-focused tool for AI-driven CAD automation. Pick it if you want agents to iterate geometry fast; skip it if you need a GUI or collaborative editing. The spec-check mode is a standout for quality control.
- AI agents designing 3D parts iteratively with a tight feedback loop
- Developers automating CAD workflows with LLMs
- Engineers prototyping with agent-driven design
- Hobbyists exploring generative CAD programmatically
- Artists needing interactive GUI modeling
- Users requiring collaborative real-time editing
- Beginners unfamiliar with Python scripting
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In short
agentcad — Open-source MCP server for AI agents to design 3D parts. Best for AI agents designing 3D parts iteratively with a tight feedback loop, Developers automating CAD workflows with LLMs, Engineers prototyping with agent-driven design. Free to use.
Viability Score
How likely is agentcad to still be operational in 12 months? Based on 4 signals — momentum (how recently it shipped), wrapper dependency, revenue model, and web presence.
Last calculated: July 2026
How we score →Key Features
- MCP server integration for coding agents (Claude Code, Cursor, Windsurf)
- Pre-execution validation catches syntax and import errors in <100ms
- Run scripts with build123d or CadQuery to produce versioned STEP files
- Render PNG views from 8 preset angles plus custom
- Export to STL, GLB, OBJ for 3D printing and web
- Inspect topology for debugging geometry issues (hollow shells, validity)
- Diff two versions to track design iteration
- Spec-check mode: measure dimensions against a JSON checklist
- Zero-boilerplate scripts with pre-injected imports
- Installable agent skill for auto-discovery by Claude Code
- Browser-based 3D viewing via three.js
- Auto GLB coloring per solid
- Dry-run mode to get metrics without consuming a version
- Override script constants via --params flag
- 17+ sections of CLI documentation
About agentcad
agentcad is an open-source MCP server and CLI that lets AI agents—like Claude Code or Cursor—design, render, and export 3D parts using Python scripting with build123d or CadQuery. It provides a tight feedback loop: agents write scripts, get pre-execution validation in under 100ms, and receive structured JSON output with geometric metrics (dimensions, volume, face count, validity) plus PNG previews. Built for developers and engineers who want to offload CAD iteration to agents, agentcad includes features like spec-check mode, version diffing, topology inspection, and multi-format export (STEP, STL, GLB, OBJ). It runs locally, requires no signup, and is free under Apache-2.0 license. Key capabilities include zero-boilerplate scripts (pre-injected imports), MCP integration for coding agents, an installable agent skill, and browser-based 3D viewing via three.js. The spec-check mode lets agents verify dimensional requirements against a JSON checklist before finalizing output. agentcad also supports dry-run mode, constant overrides via --params flag, and automatic GLB auto-coloring per solid. Compared to traditional CAD tools like Fusion 360 or Onshape, agentcad is not a GUI-first application but a backend for AI-driven design. It excels in agent-automated geometry creation but requires comfort with Python and CLI. It complements tools like build123d by adding agent-facing features like metrics, validation, and versioning.
Behind the Verdict
agentcad nails a narrow but important niche: letting AI agents design real 3D geometry without GUI overhead. The feedback loop—validate, render, measure, iterate—is fast and developer-friendly. The spec-check feature is a quiet killer: it forces agents to verify dimensions against a checklist, catching mistakes before export. We'd reach for this when automating parametric part generation or prototyping cycles where you want to script geometry changes. The main tradeoff is it demands Python fluency and comfort with CLI; there's no onboarding for non-devs. Compared to build123d alone, agentcad adds agent-specific tooling like MCP server and skill install, which closers the loop for tools like Claude Code. Where it bites: no collaborative features, no cloud sync, and exports are limited to standard formats (STEP, STL, GLB, OBJ). For quick iterative design with agents, it's hard to beat. But if you need a visual timeline or team review, you'll want a traditional CAD tool.
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Use Cases
- Design a phone stand with specific dimensions and export it for 3D printing
- Iterate on an electronics enclosure with snap-fit lid by comparing version diffs
- Reconstruct a historical object like the Wright Flyer from measured drawings using prompts
- Generate a vase profile with variable thickness and validate volume constraints
- Automate CAD design for multiple part variants via script parameter overrides
- Inspect a STEP file for geometric errors before sending to fabrication
Limitations
- agentcad currently supports Python 3.10–3.12 only.
- It runs locally and requires a Python environment with the agentcad package installed.
- The tool is CLI-heavy, so users must be comfortable with terminal commands and Python scripting.
- There is no browser-based editor or GUI; all design is script-driven.
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