Emil Kowalski design skill (emil-design-eng) review: verdict, safety and alternatives
Emil Kowalski's design skill, emil-design-eng, is one SKILL.md of UI motion and polish rules for coding agents. We rate it Recommended, 76/100, with safety grade A.
- Skill
- Emil Design Engineering (emil-design-eng)
- Publisher
- Emil Kowalski
- Verdict
- Recommended
- Score
- 76/100
- Confidence
- Moderate
- Safety grade
- A (one Markdown file; no scripts, network or credentials)
- Best for
- Web developers using CSS or Motion who want UI animation reviewed against concrete easing, duration and transform rules
- Poor fit
- React Native or native mobile motion (declined in PR #15)
- Reviewed version
- commit d16ebe6 (no tags or releases)
- Review date
- 2026-09-30
- Works in verified
- Claude Code (Sonnet 4.6, Tessl eval)
- Works in claimed
- Agent Skills-compatible agents via npx skills
- Part of
- Emil Kowalski's skills collection
- Since review
- SKILL.md unchanged; new issue #29 on trigger wording (2026-10-06)
Get the skill: emil-design-eng folder on GitHub · SKILL.md at the reviewed commit · skills.sh listing
What is Emil Kowalski's design engineering skill?
Emil Kowalski's design engineering skill, emil-design-eng, is one SKILL.md file of UI motion and polish rules for coding agents. It covers easing, durations, gestures and component details, and requires a Before/After review table.
An Agent Skill is a SKILL.md package that an agent loads on demand. Our primer explains what an Agent Skill is. Emil Kowalski, the publisher, says the skill encodes the judgment behind the Sonner and Vaul UI libraries. Read how a SKILL.md file is structured.
| Fact | Value |
|---|---|
| Publisher | Emil Kowalski |
| Files | 1 SKILL.md, 27,123 bytes, 674 lines |
| Licence | MIT |
| Version | None; no tags or releases |
| Outbound links | easing.dev and easings.co only |
| Bare invocation | Opens with a fixed greeting |
What rules does the Emil Kowalski design skill teach?
The Emil Kowalski design skill teaches four motion questions: whether to animate, why, which easing and how fast. It adds custom cubic-bezier curves, duration bands, spring settings and origin-aware popovers, with copyable CSS and Motion code.
The rules, from SKILL.md at commit d16ebe6:
- Easing: custom cubic-bezier curves, with no ease-in on UI elements.
- Duration table: 200 to 500ms for modals and drawers.
- Checklist cap: flags any UI duration over 300ms.
- Springs: used for gestures and drag.
- Swipe dismissal: a velocity threshold.
- Popovers: origin-aware scaling.
- Entrances: never from
scale(0); enter states use@starting-style. - Press feedback: a visible response on buttons.
Is the Emil Kowalski design skill worth installing?
Yes, the Emil Kowalski design skill is worth installing for web motion reviews. It scores 76/100, Recommended, at Moderate confidence, with a 1.20x Tessl lift on Sonnet 4.6. One Motion snippet is broken, and one duration rule contradicts itself.
Tessl, a skill registry that runs evals, measured that lift over 2 scenarios. Its strength is concrete, copyable values: named curves, duration tables and a review checklist.
It sits among our UI and frontend design skills ranked by verdict.
| Criterion | Score |
|---|---|
| Effectiveness | 80 |
| Reliability | 72 |
| Safety | 95 |
| Efficiency | 62 |
| Compatibility | 72 |
| Maintainability | 62 |
| Setup friction | 92 |
| Code-example correctness | 62 |
| Rule consistency | 70 |
| Concreteness of guidance | 80 |
| Instruction weight vs value | 62 |
| Trigger reliability | 55 |
| Cost of adoption | 92 |
The two defects lower only two criteria. Our methodology page explains how the 76 score is built.
How many tokens does the Emil Kowalski design skill use?
The Emil Kowalski design skill loads 6,781 tokens each time it triggers, measured from file size. Our estimate for a typical task, reviewing one 150-line component, adds 10,000 input and 1,500 output tokens on top.
| Figure | Input tokens | Output tokens | Label |
|---|---|---|---|
| SKILL.md per load | 6,781 | none | Measured file size per load |
| Typical task on top of the skill | 10,000 | 1,500 | Our estimate for a typical task |
| Typical call with the skill | 17,781 | 1,500 | Our estimate for a typical task |
At 10 uses a week, the skill alone loads 67,810 tokens. Tessl suggests splitting the file into references.
What changed since our review?
The emil-design-eng file has not changed since our review on 2026-09-30. Three new commits added other skills, and new issue #29 reports that its description lacks a trigger. The verdict stays Recommended, 76.
Checked on GitHub, 2026-10-21:
- Commits: e8a175d, 6465079 and 2d22863 landed after d16ebe6. None touched
skills/emil-design-eng/. - New skills: break-ui on 2026-10-02 and animation-performance on 2026-10-11.
- Issue #29: opened on 2026-10-06, still open and community-reported. It says the description lacks when-to-use triggers.
Is the Emil Design Eng skill safe to install?
Yes, the Emil Design Eng skill is safe to install, with safety grade A. It is one Markdown file with no scripts, hooks, network calls or credentials, and three audits pass.
What the files and audits show:
- Folder: one SKILL.md; no scripts, references, assets, hooks or MCP config.
- Network: no network or environment-variable indicators.
- Audits: Gen Agent Trust Hub, Socket and Snyk all list Pass on skills.sh, the public skills directory.
The same checks appear in our checklist for vetting a skill.
What does the community report about the Emil Kowalski design skill?
The community reports on the Emil Kowalski design skill are mixed. Tessl measured 93% impact and a 1.20x lift on Sonnet 4.6. GitHub issue #26 reproduced a frozen useSpring example on two framer-motion versions.
| Claim | Source | Date | Direction | Strength |
|---|---|---|---|---|
| 1.20x average and 93% impact over 2 scenarios on Sonnet 4.6 | Tessl evals | 2026-09 | Positive | Strong |
| Quality 58%, description 45%; prose padding, no modular references | Tessl quality review | 2026-09 | Neutral | Strong |
| useSpring mouse example never tracks on framer-motion 11.18.2 and 13.1.0 | GitHub issue #26 | 2026-08 | Negative | Strong |
| Fix for the same example closed unmerged | GitHub PR #7 | 2026-07 | Negative | Strong |
| Pinned file keeps the frozen snippet and the 300ms conflict | SKILL.md at d16ebe6 | 2026-09 | Negative | Strong |
| Base UI support requested and fixed by the maintainer | GitHub issue #12 | 2026-07 | Positive | Strong |
| Hardware-acceleration wording called too absolute | GitHub issue #5 | 2026-07 | Negative | Weak |
| Users unsure whether skills auto-load; 61 comments | GitHub issue #6 | 2026-07 | Neutral | Weak |
| React Native extension declined | GitHub PR #15 | 2026-07 | Neutral | Weak |
| 310.7K installs; three security audits pass | skills.sh | 2026-09 | Positive | Weak |
| Commentary on design taste in skill files, no testing | Roger Wong blog | 2026-05 | Neutral | Weak |
What are the Emil Design Eng skill's known failures?
The Emil Design Eng skill has two known failures at commit d16ebe6. Its Motion useSpring mouse example never tracks the pointer (issue #26). Its checklist flags durations over 300ms while its table allows 500ms drawers.
- Frozen snippet:
useSpring(mouseX * 0.1)is seeded once and never moves. Issue #26 reproduced it, and fix PR #7 closed unmerged. - Duration conflict: the table allows 200 to 500ms for modals and drawers. The checklist flags anything over 300ms.
- Disputed wording: issue #5 calls the hardware-acceleration claim too absolute (weak evidence).
- Weak trigger: Tessl scores the description 45%, and issues #6 and #29 raise the same doubt. Our guide covers why a skill fails to trigger.
- No React Native: the maintainer declined it in PR #15.
At worst, an agent ships an animation that silently does nothing.
Which agents does the Emil Kowalski design skill work with?
The Emil Kowalski design skill works in Claude Code, verified through Tessl's Sonnet 4.6 eval. Other Agent Skills hosts load the same SKILL.md through npx skills, but no run there is documented. Examples target web CSS and Motion.
| Agent | Status | Evidence |
|---|---|---|
| Claude Code (Sonnet 4.6) | Verified | Tessl eval, 2 scenarios |
| Other Agent Skills-compatible agents | Claimed via npx skills | No published run |
| React Native or native mobile | Out of scope | PR #15 declined |
Our hub lists other skills verified in Claude Code.
How do you install the Emil Kowalski design skill?
Install the Emil Kowalski design skill with the skills CLI: npx skills add emilkowalski/skills --skill emil-design-eng. The bare repo command installs the whole collection. It needs no dependencies, keys or configuration.
- Run
npx skills add emilkowalski/skills --skill emil-design-engto install only this skill. - Run
npx skills@latest add emilkowalski/skillsto install the full collection. - Copy
skills/emil-design-eng/into~/.claude/skills/for a manual install. - Invoke the skill by name in your prompt.
Official sources differ. The README uses emilkowalski/skills, while the publisher page shows npx skills add emilkowalski/skill. GitHub redirects the singular name to the plural repo. See our guide to installing skills in Claude Code.
How do you use the Emil Kowalski design skill?
Use the Emil Kowalski design skill by naming it in a request to review a component's animation. It returns a Before/After/Why table covering easing, duration, transform origin and press feedback. Check any Motion code before shipping.
Its 3 main tasks:
- Review animation code and get a Before/After/Why table of fixes.
- Decide whether and how an element animates.
- Build toast, tabs or drawer components with Sonner and Vaul details.
Skip it for React Native, or for teams that paste output without checking library APIs.
Test it yourself:
- Ask the agent to add pointer-tracking tilt using Motion.
- Look for the frozen
useSpring(mouseX * 0.1)pattern in the output.
What are the alternatives to the Emil Design Eng skill?
The closest alternatives to the Emil Design Eng skill are three evaluated skills. Emil Kowalski's Animate skill (77, Recommended) builds motion. Impeccable (67, Conditional) critiques broad design, and Taste Skill (62, Conditional) sets page direction.
| Alternative | Verdict | Score | Safety grade | When it is better |
|---|---|---|---|---|
| Animate skill verdict | Recommended | 77 | A | Building new motion from fixed tables |
| Impeccable review | Conditional | 67 | C | Broad critique and polish of an existing interface |
| Taste Skill verdict | Conditional | 62 | B | Landing pages that need a design read first |
| Anthropic Design plugin verdict | Conditional | 66 | C | Critiques, handoff specs and copy reviews |
How does emil-design-eng fit into Emil Kowalski's skills collection?
Emil-design-eng is the most installed member of Emil Kowalski's skills collection, with 310.7K skills.sh installs at review. The collection, rated 75 and Recommended, adds animate, review-animations, apple-design and other motion skills.
Skills.sh listed 13 skills and 1.8M installs at review; the publisher page listed 15 on 2026-10-21. Top five at review:
- emil-design-eng: 310.7K installs.
- review-animations: 190.2K installs.
- animation-vocabulary: 177.0K installs.
- apple-design: 174.9K installs.
- animate: 107.4K installs.
Where is the Emil Design Eng skill on GitHub?
The Emil Design Eng skill lives on GitHub in emilkowalski/skills at skills/emil-design-eng/SKILL.md, under MIT. We reviewed commit d16ebe6. The repo has no releases or tags and 47,985 stars on 2026-10-21.
- Repository: emilkowalski/skills, folder
skills/emil-design-eng/. - Reviewed commit: d16ebe60d09a5ba2afcb7054ede9d0a10c9f6128, dated 2026-09-24.
- Contributors: 3; the maintainer made 52 of 54 commits.
- Stars and forks at review: 42,391 and 2,410.
- Stars and forks on 2026-10-21: 47,985 and 2,768.
- Code-search copies: 670 GitHub hits, the original and forks included.
- File hash (sha256):
ffbe68e6…for SKILL.md.
Common questions
What is Emil Kowalski's Motion skill?
No skill named "motion" exists in emilkowalski/skills, and the mcpmarket "Emil Kowalski Motion" listing is published by nexu-io. His own motion builder is the Animate skill.
What is the Emil Kowalski apple-design skill?
It is a sibling skill in the same repo for Apple-style interface and motion on the web. We have not evaluated it.
Is the Emil Kowalski design skill free?
Yes. It is MIT-licensed and installs at no cost.
Does the Emil Kowalski design skill load automatically?
No, not reliably. Its description names no trigger (Tessl 45%; issue #29), so invoke it by name.
Does it work for React Native?
No. The maintainer declined React Native in PR #15; the collection's animate-expo skill covers it, unevaluated.
Our list of top-rated Claude skills overall ranks our published verdicts.