A command that reviews a website’s code for loading and performance issues, including large files, images, scripts, fonts and lazy loading. It estimates factors related to Core Web Vitals, the measurements Google uses for loading speed, layout movement and responsiveness.

Use it to inspect a live URL or the current project for speed problems. It helps assess bundle size, image loading, render-blocking resources, fonts and scripts that may delay the page.

It identifies likely causes of a slow site from its source code, even when real visitor timing data is unavailable. This helps focus fixes on blocking resources, oversized images and unnecessary third-party scripts.

seo-speed — Command for Claude Code by bestdeejay-design

Install

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.

Clone the repo

git clone --depth 1 https://github.com/bestdeejay-design/agent-skills

Made for: Claude Code.

Wrote 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.

README.md

[![agentmods](https://agentmods.dev/badge/commands/bestdeejay-design/agent-skills/seo-speed/github.svg)](https://agentmods.dev/commands/bestdeejay-design/agent-skills/seo-speed)

Your own site

<a href="https://agentmods.dev/commands/bestdeejay-design/agent-skills/seo-speed"><img src="https://agentmods.dev/badge/commands/bestdeejay-design/agent-skills/seo-speed/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.

Your own site · 80×15

<a href="https://agentmods.dev/commands/bestdeejay-design/agent-skills/seo-speed"><img src="https://agentmods.dev/badge/commands/bestdeejay-design/agent-skills/seo-speed.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 54 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.

When invoked 874 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

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	$0.00054	$0.00874
Opus 5	$0.00027	$0.00437
Sonnet 5	$0.00011	$0.00175
Haiku 4.5	$0.00005	$0.00087

Measured 9d ago against content hash 33dc5a7811db, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

seo-speed 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 9d 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.

skills/seo-audit/commands/seo-speed.md · 93 lines

How it starts

The opening of the file, as written. The whole thing — 93 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a web performance and technical SEO specialist. Analyze the performance of the current project to identify issues that affect speed metrics and Core Web Vitals (LCP, CLS, FID/INP).

Operating mode

If the user provides a URL (e.g. /seo-speed https://example.com):

Fetch the URL and analyze the HTML: scripts, styles, images, fonts
Identify blocking resources, unoptimized images, missing lazy loading
Note: you cannot measure real timings, but you can detect issues in the source code

Without a URL → analyze files of the current project in the file system.

1. Scan relevant files

Find and review:

Build configuration files: webpack.config.js, vite.config.js, next.config.js, astro.config.mjs
Main layout files (where scripts and styles are loaded)
All referenced images (<img>, background-image, srcset)
Web font imports (@font-face, links to Google Fonts)
Third-party scripts (analytics, chat widgets, ads)

2. Performance checklist

LCP (Largest Contentful Paint) — target: < 2.5s

Hero image has loading="eager" and fetchpriority="high" (NOT lazy)
LCP image is in HTML, not loaded via JS
Web fonts use font-display: swap or optional
Critical CSS is inline or in <head>, not blocking render

CLS (Cumulative Layout Shift) — target: < 0.1

All <img> tags have explicit width and height attributes
Ad/embed elements have reserved dimensions
Web fonts do not cause layout shift (controlled FOIT/FOUT)

INP/FID (Interaction to Next Paint) — target: < 200ms

No heavy scripts on the main thread at load time
Event listeners do not block the thread

Images

Images use modern format (WebP or AVIF)
Images outside the viewport have loading="lazy"
Images have srcset for different screen sizes
No CSS images that should be <img> (for LCP)

Scripts and CSS

Non-critical scripts have defer or async
No unused CSS loaded globally
No blocking third-party scripts in <head>

Read the full file on GitHub · 93 lines

Changes

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.

9d ago First seen · 93 lines · 54 tokens per session scan A 33dc5a7811db

Subscribe to this mod's changes

seo-speed is a command published in the GitHub repository bestdeejay-design/agent-skills (5 stars, last pushed 2d ago), licensed MIT. It adds 54 tokens to every session and 874 once invoked, about $0.0003 per session on Opus 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 2026-08-31.

CSS and styling Frontend Marketing and SEO Productivity Python ai-agents automation opencode presentation-generator

/a11y-audit

Auditoría de accesibilidad WCAG 2.2 completa con escaneo de HTML/componentes. Detecta: alt text faltante, problemas de contraste, navegación por teclado, etiquetas ARIA, gestión de focus, jerarquía de encabezados, etiquetas de formularios. Genera reporte accionable con instrucciones de remediación.

gonzalezpazmonica/savia · 75 tokens

/a11y-fix

Correcciones automáticas de accesibilidad con verificación y preview. Genera código de fix para issues detectados por /a11y-audit. Preview antes de aplicar. Verifica que no introduce nuevos problemas. Covers: alt text, ARIA attributes, focus traps, skip links, color contrast.

gonzalezpazmonica/savia · 67 tokens

seo-speed