Claude design skills, tested: hallmark vs kill-ai-slop vs visual-skills
"Design skills" for Claude actually means three different jobs: generating a design system, catching AI-sloppy output, and prompting image/video models. We installed the leading skill for each job and ran them, instead of ranking screenshots.
The three jobs, and what we tested for each
| Job | Skill | Stars (2026-07-23) | Install (measured) |
|---|---|---|---|
| Generate: give the agent taste up front | Nutlope/hallmark | 15,794 | 2.5s |
| Catch: detect & fix slop in existing code | yetone/kill-ai-slop | 708 | 2.8s |
| Prompt: brief image/video models properly | smixs/visual-skills | 103 | 2.5s |
Full test record for kill-ai-slop on its own page; hallmark and visual-skills records are summarized below from the same logs.
hallmark: the generator
Nutlope's anti-slop design skill approaches the problem from the front: it loads opinionated
design-system guidance into the agent before anything is generated, so the first draft
already avoids machine defaults. Instruction-only — SKILL.md plus references, no
runtime dependencies — which explains the clean 2.5s install and means it works identically in
Claude Code, Cursor, and Codex. At 15.8k stars it is the most adopted design skill we know
of.
kill-ai-slop: the reviewer
The opposite direction: a catalogue of 33 concrete slop tells, plus a real scanner script that reports file-and-line hits. In our test it caught all seven planted offenses in a deliberately terrible page in 0.06 seconds. Full test record on its dedicated page.
visual-skills: the art director
Two skills (video + image) that teach structured prompting for Nano Banana, GPT Image, Seedance, Kling and Veo — shot structure, emotion, multi-shot briefs. Both documented install paths work (the universal CLI, though the README only mentions manual copy). One honest note for English speakers: the README's usage examples are written in Russian; the skill bodies themselves are usable regardless, since your agent reads them fine. At 103 stars it is the smallest project here, but it was pushed the day we tested.
The combination that actually works
These are not competitors — they are stages. Generate with hallmark's rules loaded, review with kill-ai-slop's scanner before shipping, and bring in visual-skills when the deliverable is a generated image or video rather than a UI. We run the first two in that order on this very site: the layout was built under hallmark-style constraints (one accent, no gradients) and then scanned with kill-ai-slop — the only hits were the slop examples we quote on purpose.
FAQ
Do any of these need a paid API?
No. All three are instruction-layer skills; visual-skills assumes you have access to whatever image/video model you are prompting, but the skill itself is free markdown.
Can hallmark and kill-ai-slop conflict?
They agree on the big rules (kill gradients, kill emoji spam, one accent). hallmark is generative preference, kill-ai-slop is detection; when both are installed the agent treats the scanner's output as review input, which is how we use them.