browser-automation

When the user asks about browser automation, use Firefox DevTools MCP to control a real Firefox browser. ## Before Starting Always call `list_pages` first. This checks whether Firefox is already running and which pages are open. Do not assume Firefox needs to be restarted or that you need to navigate from scratch — reuse the existing session whenever possible. ## When to Use This Skill Activate this skill when the user: - Wants to automate browser interactions ("Fill out this form", "Click the login button") - Needs E2E testing ("Test the checkout flow", "Verify the login works") - Wants to browse or extract content ("Get all links on this page", "Extract prices") - Needs screenshots ("Screenshot this page", "Capture the error state") - Wants to debug ("Check for JS errors", "Show failed network requests") - Needs to profile performance ("Profile this page load") ## Core Workflow ### Step 1: Navigate and Snapshot ``` navigate_page url="https://example.com" take_snapshot ``` The snapshot returns a DOM representation with UIDs (e.g., `e42`) for each interactive element. ### Step 2: Interact with Elements Use UIDs from the snapshot: ``` fill_by_uid uid="e5" text="user@example.com" click_by_uid uid="e8" ``` ### Step 3: Re-snapshot After Changes DOM changes invalidate UIDs. Always re-snapshot after: - Page navigation - Form submissions - Dynamic content loads ``` take_snapshot # Get fresh UIDs ``` ## Quick Reference | Task | Tools | |------|-------| | Navigate | `navigate_page`, `navigate_history` | | See DOM | `take_snapshot` | | Click | `click_by_uid` | | Hover | `hover_by_uid` | | Type | `fill_by_uid`, `fill_form_by_uid`, `type_text` | | Press key | `press_key` | | Drag | `drag_by_uid_to_uid` | | Dialogs | `accept_dialog`, `dismiss_dialog` | | Screenshot | `screenshot_page`, `screenshot_by_uid` | | Debug | `list_console_messages`, `list_network_requests` | | Profile | `profiler_start`, `profiler_stop` | ## Guidelines - **Check existing session first**: Call `list_pages` before navigating — reuse the running Firefox session rather than starting fresh - **Always snapshot first**: UIDs only exist after `take_snapshot` - **Re-snapshot after DOM changes**: UIDs become stale after interactions - **Screenshots**: in Cowork (system prompt has an outputs folder host path), call `screenshot_page saveTo="<host-outputs-path>/screenshot.png"` then call `present_files` with that path. Otherwise call `screenshot_page` without `saveTo` and include the returned image directly in your reply — the user cannot see tool call outputs. - **Check for errors**: Use `list_console_messages level="error"` to catch JS issues - **Firefox only**: This MCP controls Firefox, not Chrome or Safari - **Reconfiguring Firefox**: to use a specific binary, profile, or headless mode, call `restart_firefox` with the relevant options (`firefoxPath`, `profilePath`, `headless`)