A browser-automation skill that controls Chrome or Chromium through its developer interface. It can navigate pages, interact with forms, inspect content, take screenshots, and examine browser errors or network activity.

Use it to explore websites, fill in and submit forms, capture screenshots, inspect page content, and debug browser console or network behavior.

It lets an agent test and investigate real web pages instead of relying only on source code or text descriptions.

web-browser — Skill by mitsuhiko

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/mitsuhiko/agent-stuff/web-browser

Any agent

npx skills add mitsuhiko/agent-stuff --skill web-browser

Clone the repo

git clone --depth 1 https://github.com/mitsuhiko/agent-stuff

Made for: Claude Code, Codex.

Per session 64 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,163 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.

Model	Per session	Once invoked
Fable 5	$0.00064	$0.01163
Opus 5	$0.00032	$0.00581
Sonnet 5	$0.00013	$0.00233
Haiku 4.5	$0.00006	$0.00116

Measured 2d ago against content hash 2647ee685e09, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

web-browser 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 2d ago.

The scan reads SKILL.md. This mod also ships 13 executable files (scripts/cdp.js, scripts/devices.js, scripts/dismiss-cookies.js, …), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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/web-browser/SKILL.md · 147 lines

How it starts

The opening of the file, as written. The whole thing — 147 lines — stays where its author put it; the contents beside it link to each section on GitHub.

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

Read the full file on GitHub · 147 lines

Files

What ships with it

15 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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.

2d ago First seen · 147 lines · 64 tokens per session scan A 2647ee685e09

Subscribe to this mod's changes

web-browser is a skill published in the GitHub repository mitsuhiko/agent-stuff (3,032 stars, last pushed yesterday), licensed Apache-2.0. It adds 64 tokens to every session and 1,163 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 2026-08-30.

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