ngmthaq/chrome-devtools

Chrome DevTools

Overview

A specialized skill for controlling and inspecting a live Chrome browser. This skill leverages the chrome-devtools MCP server to perform a wide range of browser-related tasks, from simple navigation to complex performance profiling.

Note: Always ask the user for access to the browser before using this skill, and ensure you have the necessary permissions to perform the intended actions.

When to Use

Use this skill when:

• Browser Automation: Navigating pages, clicking elements, filling forms, and handling dialogs.
• Visual Inspection: Taking screenshots or text snapshots of web pages.
• Debugging: Inspecting console messages, evaluating JavaScript in the page context, and analyzing network requests.
• Performance Analysis: Recording and analyzing performance traces to identify bottlenecks and Core Web Vital issues.
• Emulation: Resizing the viewport or emulating network/CPU conditions.

Tool Categories

1. Navigation & Page Management

• new_page: Open a new tab/page.
• navigate_page: Go to a specific URL, reload, or navigate history.
• select_page: Switch context between open pages.
• list_pages: See all open pages and their IDs.
• close_page: Close a specific page.
• wait_for: Wait for specific text to appear on the page.

2. Input & Interaction

• click: Click on an element (use uid from snapshot).
• fill / fill_form: Type text into inputs or fill multiple fields at once.
• hover: Move the mouse over an element.
• press_key: Send keyboard shortcuts or special keys (e.g., "Enter", "Control+C").
• drag: Drag and drop elements.
• handle_dialog: Accept or dismiss browser alerts/prompts.
• upload_file: Upload a file through a file input.

3. Debugging & Inspection

• take_snapshot: Get a text-based accessibility tree (best for identifying elements).
• take_screenshot: Capture a visual representation of the page or a specific element.
• list_console_messages / get_console_message: Inspect the page's console output.
• evaluate_script: Run custom JavaScript in the page context.
• list_network_requests / get_network_request: Analyze network traffic and request details.

4. Emulation & Performance

• resize_page: Change the viewport dimensions.
• emulate: Throttling CPU/Network or emulating geolocation.
• performance_start_trace: Start recording a performance profile.
• performance_stop_trace: Stop recording and save the trace.
• performance_analyze_insight: Get detailed analysis from recorded performance data.

Workflow Patterns

Pattern A: Identifying Elements (Snapshot-First)

Always prefer take_snapshot over take_screenshot for finding elements. The snapshot provides uid values which are required by interaction tools.

1. `take_snapshot` to get the current page structure.
2. Find the `uid` of the target element.
3. Use `click(uid=...)` or `fill(uid=..., value=...)`.

Pattern B: Troubleshooting Errors

When a page is failing, check both console logs and network requests.

1. `list_console_messages` to check for JavaScript errors.
2. `list_network_requests` to identify failed (4xx/5xx) resources.
3. `evaluate_script` to check the value of specific DOM elements or global variables.

Pattern C: Performance Profiling

Identify why a page is slow.

1. `performance_start_trace(reload=true, autoStop=true)`
2. Wait for the page to load/trace to finish.
3. `performance_analyze_insight` to find LCP issues or layout shifts.

Best Practices

• Context Awareness: Always run list_pages and select_page if you are unsure which tab is currently active.
• Snapshots: Take a new snapshot after any major navigation or DOM change, as uid values may change.
• Timeouts: Use reasonable timeouts for wait_for to avoid hanging on slow-loading elements.
• Screenshots: Use take_screenshot sparingly for visual verification, but rely on take_snapshot for logic.