Chrome DevTools Agent

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.

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.

markdown

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.

markdown

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.

markdown

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.