control-in-app-browser

control-in-app-browser is a skill for Claude Code, Codex from storybookjs/mcp. It costs 67 tokens per session (692 once invoked), scanned A, original, MIT.

A browser-control skill for opening, navigating, inspecting, testing, and interacting with pages inside Codex’s in-app browser.

In plain words
What is it for?
It works with localhost and other local targets as well as websites, and can click, type, read page state, take screenshots, and verify results.
Why use it?
It lets an agent verify visible web pages and local applications through the same browser a user can inspect.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions Codex.

Good fit It works with localhost and other local targets as well as websites, and can click, type, read page state, take screenshots, and verify results.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/storybookjs/mcp/codex-browser
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.

Any agent
npx skills add storybookjs/mcp --skill codex-browser
Clone the repo
git clone --depth 1 https://github.com/storybookjs/mcp

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 control-in-app-browser

README.md
[![agentmods](https://agentmods.dev/badge/skills/storybookjs/mcp/codex-browser/github.svg)](https://agentmods.dev/skills/storybookjs/mcp/codex-browser)
Your own site
<a href="https://agentmods.dev/skills/storybookjs/mcp/codex-browser"><img src="https://agentmods.dev/badge/skills/storybookjs/mcp/codex-browser/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for control-in-app-browser

Your own site · 80×15
<a href="https://agentmods.dev/skills/storybookjs/mcp/codex-browser"><img src="https://agentmods.dev/badge/skills/storybookjs/mcp/codex-browser.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 67 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 692 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00067 $0.00692
Opus 5.5 $0.00027 $0.00277
Sonnet 5.5 $0.00013 $0.00138
Haiku 4.5 $0.00007 $0.00069

Measured 2mo ago against content hash b04940c1c328, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

control-in-app-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 2mo 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.

agent-eval/lib/mcp/codex-browser-skill.md · 47 lines

How it starts

The opening of the file, as written. The whole thing — 47 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Browser

Use this skill for browser automation tasks such as inspecting pages, navigating, testing local apps, clicking, typing, taking screenshots, and reading visible page state.

If this skill is listed as available in the session, treat that as mandatory reading before browser work. Open and follow this skill before saying that Browser is unavailable and before falling back to standalone Playwright or other browser-control mechanisms.

Bootstrap

The browser-client module is the core entry point for browser use, and is available at .agent-eval/mcp/codex-browser-client-mock.mjs relative to the workspace root. ALWAYS import it using an absolute path composed from nodeRepl.cwd. IMPORTANT: If this path cannot be found, stop and report that the workspace is missing .agent-eval/mcp/codex-browser-client-mock.mjs.

Run browser setup code through the Node REPL js tool. In this environment the callable tool id typically appears as mcp__node_repl__js. You need the js execution tool: js_reset only clears state, and js_add_node_module_dir only changes package resolution.

Initialize the runtime once per fresh Node session, select the in-app browser, and immediately read its complete documentation:

if (globalThis.agent?.browsers == null) {
	const { setupBrowserRuntime } = await import(
		nodeRepl.cwd + '/.agent-eval/mcp/codex-browser-client-mock.mjs'
	);
	await setupBrowserRuntime({ globals: globalThis });
}
globalThis.browser = await agent.browsers.get('iab');
nodeRepl.write(await browser.documentation());

If setup succeeds but browser discovery or selection fails, read await agent.documentation.get("bootstrap-troubleshooting") before resetting the JavaScript session.

Use the browser bound to browser for tasks in this skill. The ability to interact directly with the browser is exposed through the agent.browsers.* API. Before trying to interact with it, you MUST emit and read the complete documentation returned by await browser.documentation() in one go, using the exact direct call nodeRepl.write(await browser.documentation()); shown above.

Read the full file on GitHub · 47 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. 2mo ago First seen · 47 lines · 67 tokens per session scan A b04940c1c328

Subscribe to this mod's changes

control-in-app-browser is a skill published in the GitHub repository storybookjs/mcp (271 stars, last pushed 2mo ago), licensed MIT. It adds 67 tokens to every session and 692 once invoked, about $0.0003 per session on Opus 5.5. 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 2026-09-03.

Related

control-in-app-browser compared with skills from other repositories

control-in-app-browser next to 6 skills from other repositories
ModTypeStarsLast pushLicenceScanTokensWorks with
control-in-app-browserstorybookjs/mcpSkill2712mo agoMITA67Claude Code, Codex
interactive-loginyc-software/qmSkill16kyesterdayMITA46Claude Code, Codex
pinchtab-mcppinchtab/pinchtabSkill11k10d agoMITA52Claude Code, Codex
azure-messaging-webpubsub-javamicrosoft/skillsSkill3.2kyesterdayMITA43Claude Code
cua-driverdavidondrej/skillsSkill4.3k3d agoMITA68Claude Code, Codex
open-design-browsercompozy/compozySkill2.8kyesterdayMITA56Claude Code, Codex
southwestborski/travel-hacking-toolkitSkill895yesterdayMITA40Claude Code