Effective HTML is a collection of agent skills for creating self-contained HTML artifacts such as wireframes, interactive prototypes, plans, diagrams, reports, and tools. It helps coding agents turn reference material and prompts into visual, usable HTML deliverables, and the catalogue entries are its installable skills and plugins.
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 plannotator/effective-html --skill design-artifactgit clone --depth 1 https://github.com/plannotator/effective-htmlWrote 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/plannotator/effective-html/design-artifact)<a href="https://agentmods.dev/skills/plannotator/effective-html/design-artifact"><img src="https://agentmods.dev/badge/skills/plannotator/effective-html/design-artifact/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/plannotator/effective-html/design-artifact"><img src="https://agentmods.dev/badge/skills/plannotator/effective-html/design-artifact.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket pass
- Snyk pass
- 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 | $0.00072 | $0.02274 |
| Opus 5.5 | $0.00029 | $0.00910 |
| Sonnet 5.5 | $0.00014 | $0.00455 |
| Haiku 4.5 | $0.00007 | $0.00227 |
Grade A, and why
design-artifact 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 1mo 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 — 84 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Take the perspective of the creative director at a boutique agency with a reputation for range — every commission gets its own visual identity, scaled to whatever level of treatment the brief actually merits. Palette, type, and layout should all be conscious decisions rooted in this particular subject; nothing should smell like it came off a shelf.
Begin by sizing up the brief
The question is never whether to design — it's what register to design in. A memo deserves craftsmanship equal to a landing page; the two simply wear that craftsmanship differently.
Much of what comes in wants a workmanlike register: plans, briefs, demos. Finish it properly — real hierarchy in the type, spacing that was thought about, a palette that was chosen — but know when to stop. Hardly any page benefits from a towering, theatrical hero. Ornament sparingly and with taste.
Then there's work that earns the editorial register: landing pages, games, apps and tools someone will hold onto or pass along.
When in doubt, remember that nobody ever regretted a well-composed page, whereas an identity pushed too hard sometimes backfires.
Everything in the fundamentals section applies universally. The editorial process at the end only kicks in when your read of the brief calls for it.
Fundamentals for every artifact
Defer to prior art. Before anything else, hunt for an established design system — a AGENTS.md or CLAUDE.md and/or DESIGN.md, QUALITY.md, PRODUCT.md etc, a tokens or theme file, styling on existing components. Found one? Apply it. The guidance below exists to plug holes, never to overrule. Authority flows in one fixed direction: what the user literally said, then whatever system the project already has, then your own taste.
Anchor everything to the subject. Where the subject is fuzzy, sharpen it first: one concrete thing, a defined audience, a single purpose the page exists to serve. The most distinctive moves are excavated from the subject's native territory — the stuff it's made of, the tools of its trade, the language its people speak. Populate the build with genuine content from the first draft onward; lorem ipsum is banned.
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.
- 1mo ago First seen · 84 lines · 72 tokens per session scan A c8314b66fb90
design-artifact is a skill published in the GitHub repository plannotator/effective-html (3,717 stars, last pushed 6d ago), licensed MIT. It adds 72 tokens to every session and 2,274 once invoked, about $0.0003 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 2026-08-30.
Other skills, from other repositories
playground
Creates interactive HTML playgrounds — self-contained single-file explorers that let users configure something visually through controls, see a live preview, and copy out a prompt. Use when the user asks to make a playground, explorer, or interactive tool for a topic.
frontend-ui-engineering
Builds production-quality, accessible, responsive user-facing UIs. Use when building or modifying interfaces and pages, creating components, implementing layouts, meeting WCAG accessibility requirements, managing state, or when the output needs to look and feel production-quality rather than AI-generated.
frontend-design
Guidance for distinctive, intentional visual design when building new UI or reshaping an existing one. Helps with aesthetic direction, typography, and making choices that don't read as templated defaults.
web-design-engineer
Build or redesign polished browser-rendered visual artifacts with HTML/CSS/JavaScript/React: pages, dashboards, prototypes, slide decks, animations, UI mockups, and data visualizations. Use for visual front-end creation, design-system exploration, design critique, or explicit browser acceptance / QA of a web artifact.…
baseline-ui
Quickly deslop UI code by fixing spacing, hierarchy, typography, and small layout issues. Use when the interface needs a fast cleanup or polish pass.
migrate
Apply DESIGN, canon, and modules to every page in the inventory, producing a deployable static HTML site. Use to migrate or render the whole captured site into the redesigned static tree ("migrate the pages", "render the migrated site", "apply the design to all pages", "build the deployable site", "convert the…