DOM Inspection for Debugging

When a visual bug doesn't show up in a screenshot, the DOM tells the truth. Certyn's inspect_dom tool lets AI agents examine the raw HTML structure, computed styles, and element properties — the same information you'd find in Chrome DevTools' Elements panel.

How It Works

The agent uses Chrome DevTools Protocol to query the DOM. You provide a CSS selector, and the tool returns everything about that element: its HTML, attributes, computed styles, box model dimensions, and more.

No need to open DevTools manually — the agent reads the DOM programmatically and reasons about what it finds.

What You Get

HTML structure

The outer HTML of the matched element, including all children. This reveals:

• Missing or misplaced elements
• Incorrect nesting
• Unexpected attributes or classes

Computed styles

The final, resolved CSS values after all stylesheets, inheritance, and specificity have been applied. Useful for catching:

• Colors that don't match the design system
• Font sizes or weights that are wrong
• Unexpected display, visibility, or opacity values
• Missing or incorrect z-index layering

Box model

The exact dimensions: content, padding, border, and margin. This helps debug:

• Elements that are the wrong size
• Unexpected spacing between components
• Overflow issues

Example Scenarios

Debug a misaligned button

"Inspect the submit button (selector: button[type='submit']) and check its computed margin, padding, and display properties."

Verify theme colors

"Inspect the primary heading (selector: h1) and verify the color matches our brand blue (#1a73e8)."

Check responsive layout

"Inspect the sidebar (selector: .sidebar) and check if its display property is none on mobile viewports."

Combine with simulate_device to emulate a mobile device first, then inspect the DOM to verify responsive CSS is applied correctly.

Find hidden elements

"Inspect the error message container (selector: .error-message) and check its visibility and display properties."

Validate form structure

"Inspect the login form (selector: #login-form) and check if all input elements have associated label elements."

Tips

• Use specific CSS selectors to target exactly the element you need
• Combine with screenshots to correlate visual bugs with DOM state
• Check computed styles rather than inline styles — computed values reflect the actual rendered result
• Use get_accessibility_tree alongside DOM inspection for a complete picture of element semantics and visual implementation