web_fetch — single-page apps, sites behind logins, dynamic dashboards, file uploads, or workflows that require multiple steps. For static page content, the lighter web_fetch tool is faster and cheaper.
Browser Actions
The browser tool supports 16 actions, verified againstBROWSER_TOOL_ACTIONS in packages/skills/src/builtin/platform/browser-tool-schema.ts:
Page Actions
screenshot -- Capture a screenshot
screenshot -- Capture a screenshot
Take a screenshot of the current page. The image is returned as a message attachment.
Screenshots are useful for visual verification — checking how a page looks, confirming form submissions, or capturing error states.
snapshot -- Get the accessibility tree
snapshot -- Get the accessibility tree
Get a structured representation of the page content using the accessibility tree. This is how agents “read” web pages.
Format options:
- aria — The full accessibility tree with all ARIA roles and properties. Detailed but verbose.
- ai — A condensed format designed for AI consumption. Shows interactive elements (buttons, links, inputs) with labels and references that can be used with the
actaction.
ai format is recommended for most use cases — it gives agents the information they need to interact with the page without overwhelming them with structural details.act -- Interact with page elements
act -- Interact with page elements
Interact with elements on the page. The
act action supports 11 different interaction types (called “sub-kinds”), each designed for a specific type of interaction.The
act action wraps its interaction parameters inside a request object. See the Interaction Types section below for all 11 sub-kinds and their parameters.open -- Open a new tab
open -- Open a new tab
Open a new browser tab and navigate to a URL.
SSRF validation applies to the URL (same as
navigate).pdf -- Save page as PDF
pdf -- Save page as PDF
Save the current page as a PDF document, returned as a message attachment.
Useful for archiving web pages or generating printable versions of online content.
upload -- Upload files
upload -- Upload files
Upload one or more files to a file input element on the page.
dialog -- Handle browser dialogs
dialog -- Handle browser dialogs
Respond to browser dialogs such as JavaScript alerts, confirmation prompts, and input prompts.
console -- View console output
console -- View console output
Retrieve the browser’s developer console output, including errors, warnings, and log messages.
Useful for debugging page issues or monitoring JavaScript errors.
Interaction Types (act sub-kinds)
When using theact action, the kind parameter determines what type of interaction to perform. There are 11 interaction types:
Selecting Elements
Most interaction types require aref parameter to identify which element to interact with. You can use:
- CSS selectors — Standard CSS selectors like
#login-button,.submit-btn, orinput[name="email"] - Aria references — References from the
snapshotoutput inaiformat, which label interactive elements with short identifiers
Browser Profiles
Profiles create isolated browser contexts with separate cookies, local storage, and session data. This is useful for:- Managing multiple accounts on the same website
- Testing with different user states (logged in vs. logged out)
- Keeping browsing sessions separate between different tasks
profiles action to create, list, and switch between browser profiles.
Stealth mode (anti-bot detection)
The default install provisions stock Chrome running headed via Xvfb (both--with-browser and --with-xvfb are on by default) — headed already clears the low tier of headless-detection (BrowserScan flips Robot → Normal). Still flagged by fingerprint-tier services (Cloudflare Turnstile, FingerprintJS, reCAPTCHA v3 scoring, Reddit’s secondary fingerprint check); for those, add --with-cloakbrowser. A --without-xvfb install runs plain headless Chrome; --without-browser skips the runtime entirely.
The install-time flags compose. They’re available in both the bare-metal installer (install.sh) and the Docker image (build args):
Verified results (Ubuntu 24.04 VPS, head-to-head against the same probes)
The
WEBDRIVER fail is unavoidable for any CDP-connected browser — it’s a W3C-spec observable side effect, not a fingerprint defect. CloakBrowser’s own documentation calls this out as the single irreducible cost.
Install examples
findChrome() probes ~/.cloakbrowser/chromium-*/chrome first, then platform-specific Chrome paths. Whatever was installed wins.
License note
CloakBrowser’s wrapper is MIT-licensed; the compiled binary is under a separate license — free for self-hosted use (including bringing it into your own VPS / Docker deploys), but bundling into a service you distribute to third-party customers requires a separate OEM license from CloakHQ. See the CloakBrowser binary license for the full terms.Security
The browser includes built-in security protections:- SSRF validation — The
navigateandopenactions validate URLs before loading them. The browser cannot access localhost, internal IP addresses (like10.x.x.xor192.168.x.x), or cloud metadata endpoints (like169.254.169.254). This prevents attacks where a crafted message tricks the browser into accessing your internal network. - Screenshot sanitization — Screenshots are processed and sanitized before being stored or sent.
End-to-end example: scraping a SPA
A typical multi-step workflow — visit a JavaScript-rendered dashboard, log in, navigate to a data view, and pull a value the agent can act on. The agent strings together navigate, snapshot, act, and screenshot in sequence:message tool’s attach action.
For sites that emit network calls you want to inspect, the agent can pair the browser with console (to see JS logs) and act kind: evaluate (to run JavaScript like document.querySelector(...).innerText). For high-throughput scraping that does not need rendered JavaScript, prefer web_fetch.
Related
Built-in Tools
All built-in tools including browser
Web Tools
Web search and page fetching tools
Agent Tools Overview
See all available agent tools
Config Reference
Browser and tool configuration options
