visual-verification

visual-verification is a skill for Claude Code, Codex from ColeMurray/background-agents. It costs 14 tokens per session (1,783 once invoked), scanned A, original, MIT.

A procedure for checking changes to an application's user interface using screenshots or videos. It uses a browser to open the changed interface and produces visual evidence for review.

In plain words
What is it for?
Checking UI changes, comparing before-and-after captures, testing responsive layouts, and uploading a screenshot or short video.
Why use it?
A page can work in code while still looking wrong, especially at different screen sizes. This makes the visual result available for inspection.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/colemurray/background-agents/visual-verification
Any agent
npx skills add ColeMurray/background-agents --skill visual-verification
Clone the repo
git clone --depth 1 https://github.com/ColeMurray/background-agents

Made for: Claude Code, Codex.

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.

agentmods badge for visual-verification

README.md
[![agentmods](https://agentmods.dev/badge/skills/colemurray/background-agents/visual-verification.svg)](https://agentmods.dev/skills/colemurray/background-agents/visual-verification)
Your own site
<a href="https://agentmods.dev/skills/colemurray/background-agents/visual-verification"><img src="https://agentmods.dev/badge/skills/colemurray/background-agents/visual-verification.svg" alt="Measured on agentmods" height="20"></a>
Per session 14 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,783 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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.

ModelPer sessionOnce invoked
Fable 5 $0.00014 $0.01783
Opus 5 $0.00007 $0.00892
Sonnet 5 $0.00003 $0.00357
Haiku 4.5 $0.00001 $0.00178

Measured 3d ago against content hash 0b47d292f463, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

visual-verification 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.

packages/sandbox-runtime/src/sandbox_runtime/skills/visual-verification/SKILL.md · 208 lines

How it starts

The opening of the file, as written. The whole thing — 208 lines — stays where its author put it; the contents beside it link to each section on GitHub.

visual-verification

Use this skill when the goal is to verify UI changes inside the application and return visual evidence in the Open-Inspect session.

agent-browser remains the low-level browser tool. This skill defines the workflow contract for using it reliably.

Key Fact

upload-media is a bash command installed on PATH. Run it with your Bash tool, not as an MCP tool or tool binding. For videos, use agent-browser record directly, then probe and upload the resulting MP4 with upload-media.

When To Use It

  • Verify a UI change after editing code
  • Capture before/after screenshots for comparison
  • Confirm responsive layout differences at a chosen viewport
  • Produce an uploaded screenshot or short video artifact the user can review in-session

Success Criteria

The task is not complete until all of these are true:

  1. The changed UI is opened in the browser.
  2. The capture mode is chosen explicitly: viewport screenshot, full-page screenshot, or video.
  3. The viewport is set explicitly or reported as a deliberate default.
  4. A screenshot or video is uploaded in the same prompt.
  5. The returned artifactId is reported back to the user.
  6. The response states what was verified and what dimensions/mode were used.

Required Workflow

  1. Open the target page with agent-browser open.
  2. If viewport matters, set it explicitly with agent-browser set viewport <width> <height>.
  3. Wait for the page to settle before capture.
  4. Choose one of:
    • Viewport screenshot for above-the-fold or device-specific review
    • Full-page screenshot for full document review
    • Video recording for interaction flows, animations, transitions, or multi-step behavior
  5. Upload the capture immediately with matching metadata.
  6. Report the result with the artifact ID and actual capture settings.

Default Decision Rules

  • Use a viewport screenshot when validating a specific visible state, modal, interaction, or desktop/mobile layout.
  • Use a full-page screenshot when the user asks for the whole page or when vertical content is part of the verification.
  • If the user names a device or screen size, set the viewport explicitly.
  • If the user does not specify dimensions and layout matters, choose a reasonable viewport and report it.
  • If the screenshot is intended to prove a fix, prefer stating exactly what was checked, not only that a screenshot was taken.
  • Use a video when the proof depends on seeing interaction over time, such as opening a menu, dragging, typing, navigating between states, or watching an animation complete.

Read the full file on GitHub · 208 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.

  1. 3d ago First seen · 208 lines · 14 tokens per session scan A 0b47d292f463

Subscribe to this mod's changes

visual-verification is a skill published in the GitHub repository ColeMurray/background-agents (2,712 stars, last pushed yesterday), licensed MIT. It adds 14 tokens to every session and 1,783 once invoked, about $0.0001 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 2026-08-30.

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