website-analyzer

name	website-analyzer
description	Analyze a website's UI/UX, category, style, performance, surface security, and SEO; emit structured JSON. Use for URL audits or website-cloner input. Don't use for penetration tests, full SEO audits, or App Store ASO.
license	MIT
effort	high
metadata	{"version":"1.3.0","author":"Luong NGUYEN <[e-mail]>"}

Website Analyzer

Analyzes any website URL across 6 dimensions and produces structured JSON output for downstream skills in the website-cloner suite.

When to Use

Trigger when the user asks to:

• Analyze, audit, or scan a website
• Get a performance, SEO, security, or UI/UX assessment of a URL
• Understand a website's structure, style, or category

Do not use for full penetration testing, deep security audits, or App Store ASO.

Prerequisites

1. Require a valid http:// or https:// URL and an output path or stdout destination.
2. Confirm page-fetch access is available; never bypass authentication, paywalls, or bot protections.
3. When an output path is supplied, validate that its directory exists and is writable; skip this check for stdout.
4. If any prerequisite fails, return a descriptive error with the failing input and corrective action.

Workflow

1. Fetch page content via WebFetch
2. Extract HTML structure, metadata, headings, links, images, scripts
3. Estimate performance metrics (LCP, CLS, TTFB, page weight, request count)
4. Run surface-level security checks
5. Score SEO across 5 weighted dimensions
6. Classify UI/UX layout, category, and style
7. Output structured JSON

Output

Produce structured JSON at the requested output path (or stdout):

{
  "url": "https://example.com",
  "timestamp": "2026-05-07T12:00:00Z",
  "ui_ux": {
    "layout": "single-column | two-column | grid | ...",
    "visual_hierarchy": "what draws attention first",
    "components": ["nav", "hero", "cta", "footer", ...],
    "responsive": "desktop-first | mobile-first | adaptive | unknown",
    "friction_points": ["slow nav", "missing CTA", ...]
  },
  "category": "saas-landing | portfolio | e-commerce | blog | docs | dashboard | ...",
  "category_confidence": 0.9,
   
     
      ...
     
     
     
  
   
     
     
     
     
     
     
  
   
     
     
      ...
     
     
  
   
     
     
     
     
     
     
     
     
     
       
       
       
       
       
    
  

Step 1: Fetch the Page

Use WebFetch to retrieve content:

WebFetch(url=<url>, prompt="Extract all HTML structure, meta tags, headings, links, images, scripts, styles, and any structured data (JSON-LD, Open Graph, etc.)")

If WebFetch fails (4xx, 5xx, timeout), return immediately:

{"url": "<url>", "error": "unreachable", "detail": "<error>"}

For JS-heavy SPAs where WebFetch returns minimal content, note: {"note": "SPA detected — analysis based on crawlable content only; some metrics may be incomplete"}

Step 2: Extract Structure

From fetched content, extract:

• <title>, <meta> tags (description, keywords, OG, Twitter)
• Heading hierarchy (<h1>–<h6>)
• Images with alt attributes
• Link structure and count
• Script/style count and sizes
• JSON-LD structured data
• Canonical URL
• Robots meta tag

Step 3: Estimate Performance

Metric	Method
Page weight	Sum of referenced resource sizes; estimate image sizes from layout
Request count	Count <img>, <link rel="stylesheet">, <script>, font refs
LCP (lcp_estimate_seconds)	Inferred from above-fold content size; seconds, with a 0.5-second minimum for bare HTML
CLS (cls_estimate)	Estimated from layout shift indicators (missing dimensions, late loaders); unitless
TTFB (ttfb_estimate_seconds)	Inferred from hosting signals; seconds; static → low, dynamic → moderate

All metrics are estimates from static analysis. Note this in output.

Step 4: Security Check (Surface-Level Only)

Check:

• HTTPS usage
• Mixed content (HTTP resources on HTTPS page)
• Security headers: HSTS, X-Content-Type-Options, X-Frame-Options, CSP
• Exposed metadata (dev tools, debug endpoints, sensitive data in comments)

Always label as surface-level.

Step 5: SEO Scoring

Compute each dimension's 0–100 sub-score using the rubrics below, then combine with the weights to yield the overall seo.score. Round each sub-score to the nearest integer; the final score is round(Σ weight_i × sub_i).

Dimension	Weight	Sub-score rubric (0–100)
Meta tags (title + description)	20%	Start at 0. +50 if <title> is present and 10–60 chars. +50 if <meta name="description"> is present and 50–160 chars. Subtract 25 each for: title outside 10–60, description outside 50–160, duplicate title across siblings (when crawlable). Floor at 0.
Heading structure	15%	100 if exactly one <h1> and at least one <h2>. 70 if exactly one <h1> but no <h2>. 40 if zero or multiple <h1>s. Subtract 20 if any heading level is skipped (e.g. h2 → h4). Floor at 0.
Image alt text coverage	15%	round(100 × non_empty_alt_count / total_img_count). If total_img_count == 0, report 100 (no images = no alt-text debt). Decorative images using alt="" count as "non-empty intent" only when paired with role="presentation"; otherwise count as missing.
Structured data	20%	100 if at least one valid JSON-LD block is present and parses (any schema). 60 if only Open Graph or Twitter Card meta tags are present (no JSON-LD). 30 if only microdata or RDFa. 0 if none.
Crawlability (canonical, robots, sitemap)	30%	Start at 0. +40 if a <link rel="canonical"> resolves to an absolute URL. +30 if robots.txt is fetchable and not Disallow: /. +30 if a sitemap is referenced (via robots.txt Sitemap: directive, <link rel="sitemap">, or a fetchable /sitemap.xml). Cap at 100.

When a sub-score cannot be computed (e.g. robots.txt unreachable), record the dimension as null in dimension_scores and exclude it from the weighted sum, redistributing its weight proportionally across the remaining dimensions. Note any nulls in seo.notes.

Step 6: UI/UX, Category, Style

• Layout: Infer from HTML structure (divs, sections, nav, main, footer)
• Category: saas-landing | portfolio | e-commerce | blog | docs | dashboard | marketing-site | web-app | other
• Style: Typography, color palette, spacing density, motion indicators, aesthetic vibe

Edge Cases and Error Handling

Failure	Behavior
Unreachable (4xx/5xx/timeout)	{"error": "unreachable"} — stop
JS-heavy SPA	Note limitation, proceed with crawlable content
Paywall / login	{"error": "paywall"} — stop
Redirect loop	{"error": "redirect-loop"} — stop
Empty page	{"error": "empty"} — stop

Acceptance Criteria

Verify the expected output before reporting success:

• JSON parses and contains url, timestamp, ui_ux, category, style, performance, security, and seo.
• seo.score is an integer from 0 through 100 and matches the weighted, null-adjusted dimension calculation.
• Performance estimates use lcp_estimate_seconds, unitless cls_estimate, ttfb_estimate_seconds, and total_page_weight_kb, plus an explicit static-analysis limitation.
• Every unavailable measurement is null or an error field, never an invented value.
• The output is written to the requested destination; assert the file exists and can be parsed when a path is supplied.

Step Completion Report

Emit this after analysis:

◆ Analyze Website
··································································
  Input fetched:        √ pass | × fail ([reason])
  Six dimensions:      √ pass | × partial ([missing])
  SEO calculation:     √ pass | × partial ([null dimensions])
  Output JSON:         √ pass ([path or stdout])
  Result:              PASS | PARTIAL | FAIL

Report PASS only when the JSON is valid and all six top-level dimensions are present; use PARTIAL for explicitly labeled crawlability gaps.