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Core Web Vitals

Checked
davila7·vlatest·frontend·MIT

Analyzes webpage performance metrics like loading speed, interactivity, and visual stability to identify frontend optimization opportunities.

Repository

Install on your platform

Showing Claude Code. One command installs this skill into any of the agents below.

  1. 1

    Run this in your project

    terminal
    $ npx skills add davila7/claude-code-templates --skill core-web-vitals -a claude-code

  2. Uses the open-source skills CLI and needs Node.js. Add -g to install it for your user instead of this project.

What we know about this skill

Publisher

davila7

Taken from the source listing. We haven't verified who controls this account.

Install target

Live repository

Not pinned. Installing fetches whatever the repository holds at the time you run the command.

No human has reviewed this code. The checks below are a static scan of the files at one commit — nobody has run this skill or judged whether it works. A skill runs with whatever access you give your agent, so read the source before you install it.

Automated safety checks

scanned

This skill passed all 6 checks. We read its files at one commit and looked for the things that make a skill dangerous to run — not for whether it works.

  • Declares what it does: passed

    SKILL.md parses and declares a name and a description.

    SKILL.md exists, its frontmatter parses, and it declares a name and a description.

  • No undeclared network calls: passed

    Makes no network calls.

    Every host the skill dials — from its scripts, its config endpoints or the commands it tells the agent to run — is either well-known package and API infrastructure or declared in its own frontmatter. Links in documentation are not counted.

  • No obfuscated payloads: passed

    No encoded or obfuscated payloads.

    No base64, hex or compressed blob is decoded and then executed, and no encoded shell commands.

  • No credential access: passed

    Reads no keys, tokens, keychains or credential files.

    Neither the code nor the SKILL.md instructions read SSH keys, cloud credentials, keychains, token stores, browser cookie databases or dotfiles that hold secrets.

  • No pipe-to-shell installers: passed

    No pipe-to-shell or download-and-run installers.

    No `curl … | sh` pattern, in the code or in the instructions, that runs code fetched at run time.

  • Pinned to a commit: passed

    Scanned davila7/claude-code-templates at 79182c51fb.

    The exact upstream commit SHA that was scanned is recorded, so the result refers to specific bytes.

Commit
79182c51fb
Manifest
cli-tool/components/skills/development/core-web-vitals/SKILL.md
Scanned
2 files, 579 lines
This is a static scan, not a review. It reads the skill's files; it does not run them, and it cannot tell you whether the skill is any good or whether the code does what its description says. A skill runs with whatever access you give your agent.
What each check looks for →

About this skill

What it does

This skill enables AI agents to analyze and optimize Core Web Vitals, specifically focusing on Largest Contentful Paint (LCP), First Input Delay (FID), and Cumulative Layout Shift (CLS). It helps identify performance bottlenecks in frontend code to ensure faster load times and a more stable user experience.

When to use it

  • Diagnosing why a website fails Google's PageSpeed Insights thresholds.
  • Optimizing critical rendering paths for better mobile performance.
  • Reducing layout shifts caused by dynamic content or missing image dimensions.
  • Preparing a site for SEO ranking improvements based on user experience metrics.

Key capabilities

  • LCP Analysis: Identifies slow-loading resources like images, fonts, and large text blocks that delay the main content from rendering.
  • FID Optimization: Pinpoints JavaScript execution blocking the main thread, which delays user interaction responses.
  • CLS Detection: Locates elements causing unexpected layout shifts by analyzing missing metadata or dynamic content injection points.
  • Automated Reporting: Generates specific recommendations for code changes to improve these three critical metrics.

Example prompts

  • "Analyze this React component and suggest changes to improve its Largest Contentful Paint score."
  • "Identify the JavaScript functions causing high First Input Delay in this bundle and propose lazy loading strategies."
  • "Find all elements contributing to Cumulative Layout Shift on this landing page and fix their sizing issues."

Tips & gotchas

Ensure you have access to the actual source code or a live URL, as the skill cannot analyze a site without its assets. While it focuses heavily on LCP, FID, and CLS, remember that these metrics are part of a broader performance picture including TTI (Time to Interactive) and network conditions.