PenguinHarness is a local-first platform in which multiple AI agents create, evaluate, optimize, and deploy agent applications. It is for people building AI software who want agents to generate applications and improve their own behavior through skills.
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 Prism-Shadow/penguin-harness --skill web-designgit clone --depth 1 https://github.com/Prism-Shadow/penguin-harnessWrote 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/prism-shadow/penguin-harness/web-design)<a href="https://agentmods.dev/skills/prism-shadow/penguin-harness/web-design"><img src="https://agentmods.dev/badge/skills/prism-shadow/penguin-harness/web-design.svg" alt="Measured on agentmods" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00051 | $0.04178 |
| Opus 5 | $0.00026 | $0.02089 |
| Sonnet 5 | $0.00010 | $0.00836 |
| Haiku 4.5 | $0.00005 | $0.00418 |
Grade A, and why
web-design 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 3d 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 — 128 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Web Design
Default visual language for every web page or frontend you generate, distilled from the Penguin Harness landing page and web app. The idea is GitHub-style simplicity: solid backgrounds, 1px borders instead of shadows, system fonts, one blue accent used sparingly. Depth comes from hairline borders, not shadows or gradients; dark mode is pure black, not navy. Apply these defaults unless the user explicitly asks for another style. One packaged alternative exists — the paper editorial theme below, for requests that call for a warm, print-like feel; pick one language per product and never mix them. The typography discipline, language, motion, IME, citation and responsiveness rules apply under both. Treat the user's one-line request as the whole spec: this skill fills every unstated gap, so the result is a finished page — never a wireframe that waits for styling feedback.
Before you start
If the user's message only invokes this skill (e.g. "use web-design skill") without a concrete page or interface to build, ask what they want to build. When a concrete build is already requested (an app UI, a landing page, a RAG chat interface), do not ask about styling — colors, fonts, spacing, radii and layout are all decided by the defaults below; the only question ever worth asking is what to build, never how it should look. Route by request shape: conversational or docs-QA → the chat/RAG layout; product or marketing → the page layout; tool-like apps → a sticky nav + panels composed from the components.
Non-negotiable for ANY text input that sends on Enter: never send while an IME composition is in progress (check event.isComposing, falling back to event.keyCode === 229, on keydown). For Chinese/Japanese/Korean input methods, that Enter only confirms the composed text — auto-sending on it fires half-typed messages. Details in the composer recipe below.
Ship complete
Every delivery, even from a one-line request, includes all of this unasked:
What ships with it
1 file 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.
- 3d ago Changed · -4 lines 3351c7a8a208
- 8d ago First seen · 132 lines · 51 tokens per session scan A 742cfbf640db
web-design is a skill published in the GitHub repository Prism-Shadow/penguin-harness (2,025 stars, last pushed today), licensed Apache-2.0. It adds 51 tokens to every session and 4,178 once invoked, about $0.0003 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.
Other skills, from other repositories
ui-craft
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shadcn
Manages shadcn components and projects — adding, searching, fixing, debugging, styling, and composing UI, including chat interfaces. Provides project context, component docs, and usage examples. Applies when working with shadcn/ui, component registries, presets, --preset codes, or any project with a components.json…
tailwind-design-system
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accessibility-a11y
Semantic HTML, keyboard navigation, focus states, ARIA labels, skip links, and WCAG contrast requirements. Use when ensuring accessibility compliance, implementing keyboard navigation, or adding screen reader support.
tailwind-shadcn
Tailwind CSS utility patterns with shadcn/ui component usage, theming via CSS variables, and responsive design. Use when styling components, installing shadcn components, implementing dark mode, or creating consistent design systems.
anti-slop-frontend
A mechanical, countable anti-slop checklist for AI-generated frontend. Catches the specific signatures an undirected model defaults to: AI-purple glows, Inter-everywhere, em-dashes, div-based fake screenshots, eyebrow-on-every-section, beige+brass "premium" palettes, generic Jane Doe / Acme data. Advisory layer that…