What is openscad-mcp AGENTS.md?

Contribution instructions for an OpenSCAD MCP server. OpenSCAD is a program that creates 3D models from text-based designs, while MCP is a standard way for AI tools to call external programs.

Use it when modifying the server that generates OpenSCAD source, fills in parameters, compiles models without a graphical interface, or exports 3D model and image files.

It gives contributors shared rules for architecture, predictable behavior, execution limits, and local safety.

How petrijr/openscad-mcp configures Codex and OpenCode

Reuse

Borrowing it

Nothing to install: this file belongs to petrijr/openscad-mcp. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/petrijr/openscad-mcp/main/AGENTS.md

Clone the repo

git clone --depth 1 https://github.com/petrijr/openscad-mcp

Made for: Codex, OpenCode.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/petrijr/openscad-mcp/agents-md/github.svg)](https://agentmods.dev/instructions/petrijr/openscad-mcp/agents-md)

Your own site

<a href="https://agentmods.dev/instructions/petrijr/openscad-mcp/agents-md"><img src="https://agentmods.dev/badge/instructions/petrijr/openscad-mcp/agents-md/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/petrijr/openscad-mcp/agents-md"><img src="https://agentmods.dev/badge/instructions/petrijr/openscad-mcp/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 1,251 This file is loaded in full into every session.

When invoked 1,251 The same file — it is already loaded in full.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.01251	$0.01251
Opus 5.5	$0.00500	$0.00500
Sonnet 5.5	$0.00250	$0.00250
Haiku 4.5	$0.00125	$0.00125

Measured 2mo ago against content hash 073d06d7313c, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

openscad-mcp AGENTS.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

AGENTS.md · 251 lines

How it starts

The opening of the file, as written. The whole thing — 251 lines — stays where its author put it; the contents beside it link to each section on GitHub.

AGENT.md — OpenSCAD MCP Server

Purpose of this File

This document provides guidance for humans and AI agents contributing to or extending the OpenSCAD MCP Server project.

It defines:

Project goals and non-goals
Architectural boundaries
Design principles
Coding and safety guidelines

The intent is to ensure that future contributions (human or AI-assisted) remain coherent, safe, and aligned with the original vision.

Project Mission

OpenSCAD MCP Server turns OpenSCAD into a deterministic, scriptable geometry compiler exposed via the Model Context Protocol (MCP).

The server enables MCP-compatible clients (including LLMs) to:

Generate OpenSCAD source
Inject parameters
Compile models headlessly
Export artifacts (STL, 3MF, OFF, PNG)

All while maintaining:

Predictable behavior
Clear execution boundaries
Local-first safety

This project is intentionally scoped as:

A robust, minimal MCP implementation that is easy to reason about and safe to run locally.

It also serves as a learning and architectural stepping stone toward a more complex FreeCAD MCP server.

Core Design Principles

1. Stateless by Default

Each MCP tool invocation should be self-contained
No persistent scene graph or mutable global state
Any temporary state must be explicit (e.g. temp directories)

Rationale:

Improves reproducibility
Simplifies error handling
Makes LLM-driven workflows reliable

2. OpenSCAD as a Compiler, Not an Editor

Treat OpenSCAD like a compiler:
- Input: SCAD source + parameters
- Output: artifacts or errors
Do not attempt interactive mesh editing

This aligns with OpenSCAD’s strengths and avoids unnecessary complexity.

3. Explicit Safety Boundaries

The server must not:
- Execute arbitrary Python code from MCP input
- Evaluate untrusted expressions outside OpenSCAD
- All execution should flow through the openscad CLI

Assume all SCAD input is untrusted.

Read the full file on GitHub · 251 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

2mo ago First seen · 251 lines · 1,251 tokens per session scan A 073d06d7313c

Subscribe to this mod's changes

openscad-mcp AGENTS.md is an instructions file published in the GitHub repository petrijr/openscad-mcp (4 stars, last pushed 9mo ago), licensed MIT. It adds 1,251 tokens to every session, about $0.0050 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

mcp-server openscad

openscad-mcp AGENTS.md next to 6 instructions from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
openscad-mcp AGENTS.mdpetrijr/openscad-mcp	Instructions file	4	9mo ago	MIT	A	1,251	Codex, OpenCode
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vscode oss-third-party-notices.instructions.mdmicrosoft/vscode	Instructions file	195k	today	MIT	A	5,649	GitHub Copilot
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vscode copilot-instructions.mdmicrosoft/vscode	Instructions file	195k	today	MIT	A	3,093	GitHub Copilot
vscode ai-customization.instructions.mdmicrosoft/vscode	Instructions file	195k	today	MIT	A	1,907	GitHub Copilot

openscad-mcp: Instructions file for Codex