Dev Browser

Dev Browser

Browser automation using MCP tools. Use these tools directly for all web automation tasks.

CRITICAL: No Shell Commands for Browser

NEVER use bash/shell commands to open browsers or URLs. This includes:

• open (macOS)
• xdg-open (Linux)
• start (Windows)
• Python subprocess, webbrowser, or similar
• Any script that launches a browser process

Shell commands open the user's default browser (Safari, Arc, Firefox, etc.), not the automation-controlled Chrome instance. This breaks the workflow because you cannot interact with pages opened via shell commands.

ALL browser automation MUST use the browser_ MCP tools below.*

IMPORTANT: Use browser_script for Speed

For multi-step workflows, ALWAYS use browser_script. It's 5-10x faster than individual calls.

browser_script finds elements at RUNTIME using CSS selectors - you don't need refs beforehand. This enables complete workflows in ONE call.

When to Use browser_script

• Login flows: Navigate → fill email → fill password → submit → verify
• Form submissions: Fill multiple fields → click submit → wait for result
• Multi-page workflows: Navigate → click → wait → interact → snapshot
• Any workflow with 2+ steps

Example: Complete Login Flow (ONE call)

browser_script(actions=[
  {"action": "goto", "url": "example.com/login"},
  {"action": "waitForLoad"},
  {"action": "findAndFill", "selector": "input[type='email']", "text": "user@example.com"},
  {"action": "findAndFill", "selector": "input[type='password']", "text": "secret123"},
  {"action": "findAndClick", "selector": "button[type='submit']"},
  {"action": "waitForNavigation"}
])

This executes the entire login in ONE roundtrip. A snapshot is automatically returned so you always see the final page state.

browser_script Actions

Key Features

• Runtime element discovery: findAndFill and findAndClick locate elements when the action runs
• Auto-snapshot: Final page state is always returned - no need to add snapshot action
• skipIfNotFound: Set to true to continue if element missing (useful for optional fields)
• Automatic waits: Actions like goto and clicks wait for page stability
• Error debugging: If script fails, page state at failure is captured automatically

Example: Form with Optional Field

browser_script(actions=[
  {"action": "goto", "url": "example.com/signup"},
  {"action": "waitForLoad"},
  {"action": "findAndFill", "selector": "#name", "text": "John Doe"},
  {"action": "findAndFill", "selector": "#email", "text": "john@example.com"},
  {"action": "findAndFill", "selector": "#phone", "text": "555-1234", "skipIfNotFound": true},
  {"action": "findAndClick", "selector": "button[type='submit']"},
  {"action": "waitForNavigation"}
])

Note: No need to add snapshot at the end - it's automatic!

Tools

browser_navigate(url, page_name?) - Navigate to a URL

• url: The URL to visit (e.g., "google.com" or "https://example.com")
• page_name: Optional name for the page (default: "main")

browser_snapshot(page_name?, interactive_only?) - Get the page's accessibility tree

• Returns YAML with element refs like [ref=e5]
• Use these refs with browser_click and browser_type
• interactive_only=true: Show only clickable/typeable elements (recommended!)

browser_click(x?, y?, ref?, selector?, page_name?) - Click on the page

• x, y: Pixel coordinates (default method)
• ref: Element ref from browser_snapshot (alternative)
• selector: CSS selector (alternative)

browser_type(ref?, selector?, text, press_enter?, page_name?) - Type into an input

• ref: Element ref from browser_snapshot (preferred)
• selector: CSS selector as fallback
• text: The text to type
• press_enter: Set to true to press Enter after typing

browser_screenshot(page_name?, full_page?) - Take a screenshot

• Returns the image for visual inspection
• full_page: Set to true for full scrollable page

browser_evaluate(script, page_name?) - Run custom JavaScript

• script: Plain JavaScript code (no TypeScript)

browser_pages(action, page_name?) - Manage pages

• action: "list" to see all pages, "close" to close a page

browser_keyboard(text?, key?, page_name?) - Type to the focused element

• text: Text to type (uses real keyboard events)
• key: Special key like "Enter", "Tab", "Escape", or combos like "Control+a"
• USE THIS for complex editors like Google Docs, Monaco, etc. that don't have simple input refs
• Workflow: first click to focus the editor area, then use browser_keyboard to type

browser_script(actions, page_name?) - Execute complete workflows in ONE call (see above)

• USE THIS for speed - finds elements at runtime, no refs needed beforehand
• Actions: goto, waitForLoad, waitForSelector, waitForNavigation, findAndFill, findAndClick, fillByRef, clickByRef, snapshot, screenshot, keyboard, evaluate

browser_batch_actions(urls, extractScript, waitForSelector?, page_name?) - Extract data from multiple URLs in ONE call

• USE THIS for multi-page data collection - visits each URL, runs your JS, returns compact JSON
• Provide up to 20 URLs and a JS extraction script
• Returns JSON only (no snapshots/screenshots) to minimize token usage
• Errors are skipped per-URL — one failed page won't stop the batch
• 30-second timeout per page

browser_sequence(actions, page_name?) - Simpler batching (requires refs beforehand)

• Use when you already have refs from a snapshot
• Supported actions: click, type, snapshot, screenshot, wait

browser_get_text(ref?, selector?, page_name?) - Get text content of element

• Returns the text content of the element
• Use to verify text was entered or content appeared

browser_is_visible(ref?, selector?, page_name?) - Check if element is visible

• Returns true/false
• Use to verify elements appeared after actions

browser_is_enabled(ref?, selector?, page_name?) - Check if element is enabled

• Returns true/false
• Use to verify buttons/inputs are clickable

browser_is_checked(ref?, selector?, page_name?) - Check if checkbox/radio is checked

• Returns true/false
• Use to verify form state

Workflow

Preferred: Use browser_script for complete workflows

browser_script(actions=[
  {"action": "goto", "url": "example.com"},
  {"action": "waitForLoad"},
  {"action": "findAndFill", "selector": "input[name='search']", "text": "query", "pressEnter": true},
  {"action": "waitForNavigation"}
])

→ Returns step results + final page snapshot automatically

Alternative: Step-by-step when you need to inspect first

1. browser_navigate("example.com") - Go to page
2. browser_snapshot() - Find refs like [ref=e5]
3. browser_script or browser_sequence - Execute remaining actions

CRITICAL: Verification-Driven Workflow

After EVERY action, verify it succeeded before proceeding:

1. Navigate → Take snapshot to confirm page loaded
2. Click → Take snapshot OR use browser_is_visible to confirm expected change
3. Type → Use browser_get_text to confirm text was entered
4. Form actions → Use browser_is_checked to confirm checkbox state

Example verification flow:

# Click a submit button
browser_click(ref="e5")

# VERIFY: Check if success message appeared
browser_is_visible(selector=".success-message")
# Output: true

# If false, the action may have failed - investigate before proceeding
browser_snapshot()  # See what actually happened

Why this matters:

• Pages change dynamically - refs become stale
• Actions can fail silently (overlays, loading states)
• Verification tells you WHEN to proceed vs retry
• Without verification, agents assume success and give up when things go wrong

When verification fails:

1. Take a fresh snapshot to see current page state
2. Look for error messages, loading indicators, or overlays
3. Address the blocker (dismiss modal, wait for load, etc.)
4. Retry the original action
5. Verify again

Error Recovery

When actions fail, the error message will tell you what to do:

Never give up on first failure. Take a snapshot, understand what happened, then adapt.

CRITICAL: Tab Awareness After Clicks

ALWAYS check for new tabs after clicking links or buttons.

Many websites open content in new tabs. If you click something and the page seems unchanged, a new tab likely opened.

Workflow after clicking:

1. browser_click(ref="e5") - Click the element
2. browser_tabs(action="list") - Check if new tabs opened
3. If new tab exists: browser_tabs(action="switch", index=N) - Switch to it
4. browser_snapshot() - Get content from correct tab

Example:

# Click a link that might open new tab
browser_click(ref="e3")

# Check tabs - ALWAYS do this after clicking!
browser_tabs(action="list")
# Output: Open tabs (2):
# 0: https://original.com
# 1: https://newpage.com
#
# Multiple tabs detected! Use browser_tabs(action="switch", index=N) to switch to another tab.

# New tab opened! Switch to it
browser_tabs(action="switch", index=1)
# Output: Switched to tab 1: https://newpage.com
#
# Now use browser_snapshot() to see the content of this tab.

# Now snapshot the new tab
browser_snapshot()

Signs you might be on the wrong tab:

• Page content hasn't changed after clicking a link
• Expected elements not found in snapshot
• URL is still the old URL after navigation

When to check tabs:

• After clicking any link
• After clicking "Open", "View", "Details" buttons
• After clicking external links
• When page content doesn't match expectations

Examples

Google Search (ONE call with browser_script)

browser_script(actions=[
  {"action": "goto", "url": "google.com"},
  {"action": "waitForLoad"},
  {"action": "findAndFill", "selector": "textarea[name='q']", "text": "cute animals", "pressEnter": true},
  {"action": "waitForNavigation"}
])

Returns: step results + final page snapshot (automatic)

Complete Login Flow (ONE call)

browser_script(actions=[
  {"action": "goto", "url": "example.com/login"},
  {"action": "waitForLoad"},
  {"action": "findAndFill", "selector": "input[type='email']", "text": "user@example.com"},
  {"action": "findAndFill", "selector": "input[type='password']", "text": "mypassword"},
  {"action": "findAndClick", "selector": "button[type='submit']"},
  {"action": "waitForNavigation"}
])

Returns: step results + final page snapshot (automatic)

Multi-Step Checkout (ONE call)

browser_script(actions=[
  {"action": "goto", "url": "example.com/checkout"},
  {"action": "waitForLoad"},
  {"action": "findAndFill", "selector": "#name", "text": "John Doe"},
  {"action": "findAndFill", "selector": "#address", "text": "123 Main St"},
  {"action": "findAndFill", "selector": "#city", "text": "New York"},
  {"action": "findAndFill", "selector": "#zip", "text": "10001"},
  {"action": "findAndClick", "selector": "button.submit"},
  {"action": "waitForNavigation"}
])

Returns: step results + final page snapshot (automatic)

Batch Data Extraction (ONE call with browser_batch_actions)

When you need data from multiple pages (e.g. search results, listings, product comparisons), first collect the URLs, then extract data in bulk:

Step 1: Use browser_evaluate or browser_script to collect URLs from a search results page:

browser_evaluate(script="return [...document.querySelectorAll('a.listing-link')].map(a => a.href)")

Step 2: Extract data from all URLs in one call:

browser_batch_actions({
  urls: ["https://example.com/listing/1", "https://example.com/listing/2", "..."],
  extractScript: "return { title: document.querySelector('h1')?.textContent, price: document.querySelector('.price')?.textContent, details: document.querySelector('.details')?.textContent?.slice(0, 300) }",
  waitForSelector: "h1"
})

Returns: compact JSON with results for each URL — no snapshots, no screenshots, minimal tokens.

When to use browser_batch_actions vs browser_script:

• browser_batch_actions: Visiting multiple URLs to extract data from each. No interaction needed per page.
• browser_script: Performing a workflow on a single page (fill forms, click buttons, navigate).

Google Docs

IMPORTANT: For Google Docs/Sheets/Slides, navigate directly and use browser_keyboard:

browser_navigate(url="docs.google.com/document/create")
browser_click(x=640, y=300)  # Focus editor
browser_keyboard(text="Hello, this is my document")
browser_keyboard(key="Enter")
browser_keyboard(text="Second paragraph")
browser_screenshot()  # Verify

Direct URLs:

• New Doc: docs.google.com/document/create
• New Sheet: docs.google.com/spreadsheets/create
• New Slide: docs.google.com/presentation/create

Login Pages

When you encounter a login page (e.g., Google Sign-In, OAuth screens, authentication prompts):

• Do NOT say you cannot log in or suggest alternative approaches
• Instead, ASK the user to log in manually in the browser window
• Take a screenshot to show the user the login page
• Say something like: "I've reached a login page. Please log in to your account in the browser window, then let me know when you're done."
• WAIT for the user to confirm they've logged in before continuing
• After the user confirms login, take another screenshot to verify you're past the login screen
• Then continue with the original task

This interactive login flow is essential because:

• Users expect to authenticate themselves for security
• Many services require human verification (CAPTCHAs, 2FA)
• The agent should not give up on tasks that require authentication

Filesystem

For saving/downloading content:

• Use browser's native download (click download buttons, Save As)
• Chrome handles downloads with its own permissions
• For text/data, copy to clipboard so users can paste where they want

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