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/dallay/agentsync/core-web-vitalsnpx skills add dallay/agentsync --skill core-web-vitalsgit clone --depth 1 https://github.com/dallay/agentsyncWhat 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 | $0.00066 | $0.02987 |
| Opus 5 | $0.00033 | $0.01494 |
| Sonnet 5 | $0.00013 | $0.00597 |
| Haiku 4.5 | $0.00007 | $0.00299 |
Grade A, and why
core-web-vitals 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.
This is a copy
86% identical to core-web-vitals — 61 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 469 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Core Web Vitals optimization
Targeted optimization for the three Core Web Vitals metrics that affect Google Search ranking and user experience.
The three metrics
| Metric | Measures | Good | Needs work | Poor |
|---|---|---|---|---|
| LCP | Loading | ≤ 2.5s | 2.5s – 4s | > 4s |
| INP | Interactivity | ≤ 200ms | 200ms – 500ms | > 500ms |
| CLS | Visual Stability | ≤ 0.1 | 0.1 – 0.25 | > 0.25 |
Google measures at the 75th percentile — 75% of page visits must meet "Good" thresholds.
LCP: Largest Contentful Paint
LCP measures when the largest visible content element renders. Usually this is:
- Hero image or video
- Large text block
- Background image
<svg>element
Common LCP issues
1. Slow server response (TTFB > 800ms)
Fix: CDN, caching, optimized backend, edge rendering
2. Render-blocking resources
<!-- ❌ Blocks rendering -->
<link rel="stylesheet" href="/all-styles.css">
<!-- ✅ Critical CSS inlined, rest deferred -->
<style>/* Critical above-fold CSS */</style>
<link rel="preload" href="/styles.css" as="style"
onload="this.onload=null;this.rel='stylesheet'">
3. Slow resource load times
<!-- ❌ No hints, discovered late -->
<img src="/hero.jpg" alt="Hero">
<!-- ✅ Preloaded with high priority -->
<link rel="preload" href="/hero.webp" as="image" fetchpriority="high">
<img src="/hero.webp" alt="Hero" fetchpriority="high">
4. Client-side rendering delays
// ❌ Content loads after JavaScript
useEffect(() => {
fetch('/api/hero-text').then(r => r.json()).then(setHeroText);
}, []);
// ✅ Server-side or static rendering
// Use SSR, SSG, or streaming to send HTML with content
export async function getServerSideProps() {
const heroText = await fetchHeroText();
return { props: { heroText } };
}
LCP optimization checklist
- [ ] TTFB < 800ms (use CDN, edge caching)
- [ ] LCP image preloaded with fetchpriority="high"
- [ ] LCP image optimized (WebP/AVIF, correct size)
- [ ] Critical CSS inlined (< 14KB)
- [ ] No render-blocking JavaScript in <head>
- [ ] Fonts don't block text rendering (font-display: swap)
- [ ] LCP element in initial HTML (not JS-rendered)
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 First seen · 469 lines · 66 tokens per session scan A 6dc14b8483a0
core-web-vitals is a skill published in the GitHub repository dallay/agentsync (54 stars, last pushed 3d ago), licensed MIT. It adds 66 tokens to every session and 2,987 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. It is 86% identical to core-web-vitals, differing in 61 lines, and is treated as a copy.
Other skills, from other repositories
reskin
Author a NEW skin for the reskinnable-demo app. A skin is a self-contained domain plugin under src/skins/ / that implements the frozen Skin contract (src/shell/skin-contract.ts) to swap the app's entire experience — brand, theme, layout, pages, tools, data, and agent — as a live sales demo. Use when the user says "add…
web-animation-design
Design and implement web animations that feel natural and purposeful. Use this skill proactively whenever the user asks questions about animations, motion, easing, timing, duration, springs, transitions, or animation performance. This includes questions about how to animate specific UI elements, which easing to use…
tailwind-v4
Tailwind CSS v4 usage guide and v3-to-v4 differences. This skill should be used when writing, reviewing, or refactoring any Tailwind CSS code in this repo. Triggers on tasks involving Tailwind classes, @theme blocks, CSS-first configuration, or cleanup of v3-era syntax.
bento
Modular grid layout with card-like blocks, clear hierarchy, soft spacing, and subtle visual contrast for organized, scannable interfaces.
codex
A radically minimal, blank-canvas interface built as a pure edge-to-edge surface, with almost no color and typography carrying the visual weight. Black serves as the only filled color, the only divider, and the sole surface tone cards.
fiction
A playful, energetic, cartoonesque interface inspired by friendly children's-book illustrations — warm cream backgrounds, big bold custom display typography, saturated brand color blocks, thick black outlines, generously rounded shapes.