Agent-Skills.md

Agent Skills: Web Browser Skill

Allows to interact with web pages by performing actions such as clicking buttons, filling out forms, and navigating links. It works by remote controlling Google Chrome or Chromium browsers using the Chrome DevTools Protocol (CDP). When Claude needs to browse the web, it can use this skill to do so.

UncategorizedID: mitsuhiko/agent-stuff/web-browser

Repository

mitsuhiko/agent-stuff
mitsuhikoLicense: Apache-2.0
1,797123

Install this agent skill to your local

pnpm dlx add-skill https://github.com/mitsuhiko/agent-stuff/tree/HEAD/skills/web-browser

Skill Files

Browse the full folder contents for web-browser.

Download Skill

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skills/web-browser/SKILL.md

Skill Metadata

Name
web-browser
Description
"Automate and interact with web pages through Chrome or Chromium using the Chrome DevTools Protocol (CDP): navigate, click, fill forms, inspect content, take screenshots, and debug console or network activity. Use when an agent needs a real browser. Prefer headless Chrome unless visible browser interaction is required."

Web Browser Skill

Minimal CDP tools for collaborative site exploration.

Start Chrome (Prefer Headless)

./scripts/start.js --headless            # Recommended: isolated reusable profile
./scripts/start.js --headless --profile  # Headless with a copy of your profile
./scripts/start.js                       # Visible browser window when needed
./scripts/start.js --headless --reset-profile  # Clear cached profile before launch

Starts Chrome with remote debugging (default port :9222). Agents should use --headless by default because it is less disruptive and supports navigation, evaluation, screenshots, emulation, and logging. User extensions are disabled for headless launches; a copied profile still provides its cookies and other browser state, but extension-based features are unavailable. Headed launches continue to load extensions normally. Use headed mode only when a person needs to see or interact with the browser, such as for pick.js, manual authentication, or debugging a headless-specific difference.

The start script only reuses a running browser when its profile and launch settings match. Close the running skill browser before switching between headless and headed mode.

Profile behavior:

  • Default mode uses: ~/.cache/agent-web/browser/fresh-profile
  • --profile mode uses: ~/.cache/agent-web/browser/profile-copy
  • The skill does not attach to your live Chrome profile directly
  • If :9222 is already used by an unknown instance, start will fail instead of reusing it

If Chrome is installed in a non-standard location, set:

BROWSER_BIN=/path/to/chrome ./scripts/start.js --headless

Optional debug endpoint override:

BROWSER_DEBUG_PORT=9333 ./scripts/start.js --headless

Navigate

./scripts/nav.js https://example.com
./scripts/nav.js https://example.com --new

Navigate current tab or open new tab.

Device Emulation (Mobile)

./scripts/emulate.js --list
./scripts/emulate.js iphone-14
./scripts/emulate.js pixel-7 --landscape
./scripts/emulate.js --reset

Set an active device emulation preference (viewport, DPR, touch, UA) for browser skill commands. Use --reset to clear.

Commands like nav.js, eval.js, pick.js, dismiss-cookies.js, and screenshot.js automatically apply the active preference.

Evaluate JavaScript

./scripts/eval.js 'document.title'
./scripts/eval.js 'document.querySelectorAll("a").length'
./scripts/eval.js 'document.querySelector("button")?.click(); "clicked"'
./scripts/eval.js 'await Promise.resolve(document.title)'
./scripts/eval.js 'JSON.stringify(Array.from(document.querySelectorAll("a")).map(a => ({ text: a.textContent.trim(), href: a.href })).filter(link => !link.href.startsWith("https://")))'

Execute JavaScript in the active tab. Input can be an expression or statement list; the console-style completion value is printed and promises/top-level await are awaited. Be careful with string escaping, best to use single quotes.

Screenshot

./scripts/screenshot.js
./scripts/screenshot.js --full-page
./scripts/screenshot.js --device iphone-14
./scripts/screenshot.js --device pixel-7 --full-page

Takes a screenshot and returns a temp file path.

  • Default: current viewport
  • --full-page: captures full document height
  • --device <preset>: temporary mobile emulation for that screenshot only

Pick Elements

./scripts/pick.js "Click the submit button"

Interactive element picker. Click to select, Cmd/Ctrl+Click for multi-select, Enter to finish. This requires headed Chrome; launch start.js without --headless.

Dismiss Cookie Dialogs

./scripts/dismiss-cookies.js          # Accept cookies
./scripts/dismiss-cookies.js --reject # Reject cookies (where possible)

Automatically dismisses EU cookie consent dialogs.

Run after navigating to a page:

./scripts/nav.js https://example.com && ./scripts/dismiss-cookies.js

Quick Mobile Debug Flow

./scripts/start.js --headless
./scripts/nav.js https://example.com
./scripts/emulate.js iphone-14
./scripts/nav.js https://example.com      # reload with mobile UA
./scripts/dismiss-cookies.js
./scripts/screenshot.js --full-page

Background Logging (Console + Errors + Network)

Automatically started by start.js and writes JSONL logs to:

~/.cache/agent-web/logs/YYYY-MM-DD/<targetId>.jsonl

Manually start:

./scripts/watch.js

Tail latest log:

./scripts/logs-tail.js           # dump current log and exit
./scripts/logs-tail.js --follow  # keep following

Summarize network responses:

./scripts/net-summary.js