Open URL in Firefox. Starts a new browser session if none is running.

With enable_bidi=True (default) the session automatically captures: • All JavaScript exceptions (file, line, column, stack trace) • All console.* output (log / warn / error / info / debug) • All network requests with status codes and durations

geckodriver sources (priority order):

1. GECKODRIVER_PATH env → 2. apt install gecko-driver → 3. webdriver-manager

Close the browser session. All buffered DevTools data is discarded.

Session state, geckodriver info, BiDi status and buffer sizes.

MAIN DIAGNOSTIC TOOL — returns a complete DevTools report in one call:

• js_errors — all JavaScript exceptions with file, line, column, stack • console_errors — console.error() and console.warn() output • failed_resources — CSS / JS / images / fonts that returned 4xx/5xx or failed to load • slow_resources — requests that took longer than 2 s

Use this after navigating to a page or after triggering a UI action. Equivalent to opening DevTools and checking the Console + Network tabs.

Return all JavaScript exceptions captured since browser_open.

Each entry contains: ts — ISO 8601 timestamp type — error type (e.g. 'TypeError', 'ReferenceError') text — error message url — source file URL line — line number in source file column — column number stack — full stack trace

This is the primary tool for finding which JS file and line causes a bug.

Return buffered browser console messages.

Each entry: ts, level, text, url (source file), line. Covers console.log / warn / error / info / debug.

Return network requests that FAILED — 4xx / 5xx status or DNS / connection errors.

This is how the agent detects broken CSS files, missing JS bundles, unavailable fonts, or failed API calls that cause layout or functionality issues.

Each entry: ts, method, url, type, status (0 = connection failed), duration_ms, failed (bool), error (error description).

Return all captured network requests with filtering options.

Useful for auditing which CSS/JS files are loaded, checking API response times, or finding resources that are unexpectedly missing from the page.

Clear all buffered console, JS error, and network entries.

Call this before navigating to a new page to get a clean baseline, so subsequent devtools_* calls only reflect the new page's activity.

Attach (or re-attach) WebDriver BiDi listeners to the running session.

Use if the session was opened with enable_bidi=False, or if listeners were lost after a page crash.

Take a PNG screenshot for visual / layout / CSS diagnosis.

Capture the full page to spot broken layout, or pass a CSS selector to isolate a specific component (header, nav, modal…). The agent can use this to identify misaligned elements, invisible text, broken flex/grid layouts, or unstyled components.

Return computed (final applied) CSS properties of an element.

Use this to understand why an element looks wrong: • Is it display:none or visibility:hidden? • What color / font is actually applied? • Is a CSS variable resolving correctly? • Are grid/flex dimensions what you expect?

Returns a dict of {property: computed_value}.

Return detailed info about a DOM element for debugging:

• outerHTML — the element's markup (first 4000 chars) • bounding_box — position and size on screen (x, y, width, height) • visible — whether the element is actually visible • in_viewport — whether it's within the visible scroll area • attributes — all HTML attributes • aria — ARIA role, name, label, disabled, hidden • child_count — number of child elements • text_content — visible text (first 500 chars)

Use this to diagnose elements that should be visible but aren't, or to understand the structure around a broken component.

Return CSS custom properties (variables) defined on :root.

Helps diagnose theming issues: missing tokens, wrong colour values, variables that weren't loaded because a CSS file failed to fetch.

Return the of the current page.

Return the current URL.

Return the full HTML source of the current page.

Get visible text content of the page or a specific element.

Return the value of an HTML attribute on an element.

Click an element.

Type text into an input field.

Select an in a dropdown.

Execute JavaScript and return the result as a string.

Wait until an element is visible on the page.

Navigate to a URL in the existing session (keeps BiDi listeners active).

Navigate back.

Navigate forward.

Reload the current page.

Switch into an or back to the main document.