Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add ForgeCAD/forgecad-public-kit --skill forgecad-design-specgit clone --depth 1 https://github.com/ForgeCAD/forgecad-public-kitWrote 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.
[](https://agentmods.dev/skills/forgecad/forgecad-public-kit/forgecad-design-spec)<a href="https://agentmods.dev/skills/forgecad/forgecad-public-kit/forgecad-design-spec"><img src="https://agentmods.dev/badge/skills/forgecad/forgecad-public-kit/forgecad-design-spec/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.
<a href="https://agentmods.dev/skills/forgecad/forgecad-public-kit/forgecad-design-spec"><img src="https://agentmods.dev/badge/skills/forgecad/forgecad-public-kit/forgecad-design-spec.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 1 finding, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium Excessive Agency · line 115 Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
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 | $0.00034 | $0.02225 |
| Opus 5 | $0.00017 | $0.01112 |
| Sonnet 5 | $0.00007 | $0.00445 |
| Haiku 4.5 | $0.00003 | $0.00222 |
Grade A, and why
forgecad-design-spec 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 10d 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.
How it starts
The opening of the file, as written. The whole thing — 133 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Design Spec
The design document — a git-committed, diff-reviewed markdown file — is the source of truth. Not the code, not the chat, not your head. You iterate it by commit-and-review, and the git diff is the review artifact.
Validate the design by mentally operating the thing, step by step. Walk it as someone assembles, uses, or moves it. The step with no answer — "how does the servo get inside the housing?" — is the real design gap. A spec that reads complete on the page can still hide a hole that only surfaces when you try to put it together in your head. State each gap falsifiably: not "tolerances might be tight" but "the 12mm arm cantilevers under gripping load, may flex >0.5mm."
Every number has a reason; the narrative comes before the numbers. Describe the object as if over the phone, then derive each value and show its math: wallThickness = 2.4mm = 6 × 0.4mm nozzle. The design is implementation-blind — shaped by the object, never by what the ForgeCAD API makes easy. Manufacturing process is one of those reasons — a design decision you weigh, never a default you inherit (never assume FDM/printing).
A vague request is a set of decisions you make honestly, not information to extract. No placeholders ("appropriate motor"); choose a defensible value, show why, continue. The Decisions table fills only after user review, so the loop stays in the document.
Altitude — three phases, one document trail
| Phase | When | Output |
|---|---|---|
| Intake | request is fuzzy / process unspecified | engineering brief + master prompt |
| HLD | design is wrong in approach, alternatives exist | <name>-hld.md |
| LLD | decisions locked, or a simple single-body part | <name>-lld.md |
The HLD carries only decision-driving dimensions and genuinely-different alternatives; the LLD carries enough that someone builds from it alone. Speccing every tolerance in an HLD, or revisiting locked decisions in an LLD, is an altitude error — back up. Simple parts skip straight from HLD to code, or from a request to an LLD.
What ships with it
2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 10d ago First seen · 133 lines · 34 tokens per session scan A ceaae22fe5ba
forgecad-design-spec is a skill published in the GitHub repository ForgeCAD/forgecad-public-kit (931 stars, last pushed 2mo ago), licensed MIT. It adds 34 tokens to every session and 2,225 once invoked, about $0.0002 per session on Opus 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 2026-08-30.
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