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 agentmods add skills/fusengine/agents/design-systemnpx skills add fusengine/agents --skill design-systemgit clone --depth 1 https://github.com/fusengine/agentsWrote 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/fusengine/agents/design-system)<a href="https://agentmods.dev/skills/fusengine/agents/design-system"><img src="https://agentmods.dev/badge/skills/fusengine/agents/design-system.svg" alt="Measured on agentmods" height="20"></a>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 | $0.00031 | $0.02050 |
| Opus 5 | $0.00015 | $0.01025 |
| Sonnet 5 | $0.00006 | $0.00410 |
| Haiku 4.5 | $0.00003 | $0.00205 |
Grade C, and why
design-system scanned grade C with 1 finding 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 yesterday.
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.
Hidden instructionshighPrompt injection
Directives inside HTML comments, invisible characters or bidirectional overrides are read by the model and not by the person reviewing the file.
<!-- Grounding: grounding-corpus.md §B (thresholds), §H (kept anchors); harness-contract.md invariant #2 (design-system.md format) + #3 (this file's read-path triggers harness phase 1). --> How it starts
The opening of the file, as written. The whole thing — 138 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Also defines the canonical output format of design-system.md — the file the harness gates on — including its 4 hard requirements (the ## Design Reference heading, a real inspiration URL, at least one chroma-positive OKLCH token, and the hard-forbidden font exclusions).
This is routing step 1 of design-method/SKILL.md: read it before design-web, design-webapp, design-ios, or design-android, and before picking or auditing a single color/type/spacing value.
Design System — Token Core
Single source for token strategy — not values, values live in references/*.md and are
read from there, never re-derived here. design-method/SKILL.md reads this file
unconditionally as routing step 1, once per task, before dispatching to any move or
target skill — that read is also what advances the harness past phase 0. If a design
question is purely about a token (a color, a type pair, a spacing value) this file plus its
reference index already answers it; otherwise continue back into design-method's routing.
Color strategy
- OKLCH only for new tokens:
oklch(L% C H). Never hex/HSL/RGB for anything you're defining fresh (existing legacy tokens in an inherited codebase are a different problem — don't rewrite what wasn't asked for). - Neutrals — tint every neutral toward the brand hue, chroma 0.005–0.015. Never a
pure gray (chroma 0), never
#000/#fff. - Accent commitment — pick the strategy BEFORE picking hues:
- Restrained — tinted neutrals + one accent ≤10% of surface. Product register default.
- Committed — one saturated color carries 30–60% of surface. Brand register default.
- Full palette (3–4 named roles) / Drenched (surface IS the color) — brand
campaigns, product data-viz. See
design-method/references/register/brand.md§4 andregister/product.md§1 for which strategy each register defaults to and when to deviate.
- Reduce chroma as lightness approaches 0 or 100 — high chroma at the extremes reads garish.
- Mechanics:
references/oklch-system.md. Concrete per-sector values:references/sector-palettes.md. Contrast floors:references/contrast-ratios.md— WCAG AA 4.5:1 body text / 3:1 large text + UI components (AAA 7:1 where feasible).
What ships with it
34 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.
- references/breakpoint-patterns.md 1.9 KB
- references/color-mapping.md 2.4 KB
- references/color-system.md 5.9 KB
- references/complex-themes.md 2.7 KB
- references/container-queries.md 2.1 KB
- references/contrast-ratios.md 3.4 KB
- references/design-read-dials.md 7.6 KB
- references/edge-cases.md 2.4 KB
- references/fluid-typography.md 1.9 KB
- references/forbidden-fonts.md 2.1 KB
- references/gradients-guide.md 6.0 KB
- references/identity-brief.md 2.8 KB
- references/image-handling.md 2.4 KB
- references/motion-personality.md 3.3 KB
- references/multi-brand.md 3.2 KB
- references/oklch-system.md 4.3 KB
- references/sector-palettes.md 14 KB
- references/spacing-density.md 2.9 KB
- references/tailwind-config.md 2.1 KB
- references/tailwind-performance.md 2.5 KB
- references/tailwind-utilities.md 4.1 KB
- references/templates/design-system-creative.md 3.5 KB
- references/templates/design-system-devtool.md 3.4 KB
- references/templates/design-system-ecommerce.md 3.4 KB
- references/templates/design-system-fintech.md 3.3 KB
- references/templates/design-system-template.md 3.9 KB
- references/templates/palette-template.md 4.2 KB
- references/theme-presets.md 3.2 KB
- references/typography-pairs.md 7.0 KB
- references/typography.md 5.0 KB
- references/ui-hierarchy.md 2.5 KB
- references/ui-spacing.md 3.0 KB
- references/ui-trends-2026.md 6.5 KB
- references/visual-technique-matrix.md 4.5 KB
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.
- yesterday First seen · 138 lines · 31 tokens per session scan C c3d51b350bbe
design-system is a skill published in the GitHub repository fusengine/agents (25 stars, last pushed 1mo ago), licensed MIT. It adds 31 tokens to every session and 2,050 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it C with 1 finding (hidden instructions). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.
Other skills, from other repositories
designing-interfaces
Creates a design system for software with a UI. Use when a project has a user interface and architecture is confirmed — whether creating from scratch or extracting patterns from existing code.
evaluate
Run accessibility checks and discover issues mapped to WCAG criteria.
guidelines
Package all brand elements into a complete brand guidelines document.
visual
Define visual identity — colors, typography, logo usage, and imagery style.
report
Generate a structured accessibility audit report with remediation guidance.
a11y
Review work through the lens of an accessibility specialist.