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/serkan-ozal/browser-devtools-claude/visual-testingnpx skills add serkan-ozal/browser-devtools-claude --skill visual-testinggit clone --depth 1 https://github.com/serkan-ozal/browser-devtools-claudeWhat 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 | $0.00032 | $0.00565 |
| Opus 5 | $0.00016 | $0.00282 |
| Sonnet 5 | $0.00006 | $0.00113 |
| Haiku 4.5 | $0.00003 | $0.00056 |
Grade A, and why
visual-testing 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.
How it starts
The opening of the file, as written. The whole thing — 73 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Visual Testing Skill
Perform visual testing and UI verification using screenshots and DOM inspection.
When to Use
This skill activates when:
- User wants to verify UI appearance
- User asks to compare page with design
- User needs responsive design testing
- User wants to check for visual regressions
- User mentions UI bugs or styling issues
Capabilities
Screenshot Capture
- Full page or element screenshots (
content_take-screenshot) —selectororreffor element - Annotated screenshots —
annotate: trueoverlays numbered labels [1],[2],… mapping to ARIA refs (e1,e2). UseannotateContentfor headings,cursorInteractivefor div/span buttons - PDF generation (
content_save-as-pdf)
Important: Do not use screenshot to understand page structure. Call a11y_take-aria-snapshot first, then screenshot for visual verification.
Responsive Testing
- Resize viewport (
interaction_resize-viewport) - Test mobile, tablet, desktop breakpoints
- Verify responsive behavior
Design Comparison
- Compare with Figma designs (
figma_compare-page-with-design) - Visual similarity analysis
- Identify design deviations
DOM Inspection
- Get HTML structure (
content_get-as-html) - Check CSS classes and styles
- Verify element presence and visibility
Viewport Presets
| Device | Width | Height |
|---|---|---|
| Mobile S | 320px | 568px |
| Mobile M | 375px | 667px |
| Mobile L | 425px | 812px |
| Tablet | 768px | 1024px |
| Laptop | 1366px | 768px |
| Desktop | 1920px | 1080px |
Testing Workflow
- Navigate: Go to page under test
- Wait: Network idle, page fully loaded
- ARIA snapshot first: Get refs (e1, e2, …) before screenshot
- Capture: Take baseline or annotated screenshot
- Resize: Test different viewports
- Interact: Use refs (e1) for clicks; test hover, modals
- Compare: Check against expected design
- Document: Report visual issues
Common Checks
- Element visibility at breakpoints
- Text overflow and truncation
- Image aspect ratios
- Color and typography consistency
- Spacing and alignment
- Interactive state styling
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 · 73 lines · 32 tokens per session scan A a4ec9d198b35
visual-testing is a skill published in the GitHub repository serkan-ozal/browser-devtools-claude (8 stars, last pushed 5mo ago), licensed MIT. It adds 32 tokens to every session and 565 once invoked, about $0.0002 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.
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