Webapp Testing Skill - Browser Testing with Claude

Source: Content adapted from anthropics/skills (MIT). Last synced July 8, 2026, against the April 20, 2026 upstream update.

Overview

The official description: "Toolkit for interacting with and testing local web applications using Playwright. Supports verifying frontend functionality, debugging UI behavior, capturing browser screenshots, and viewing browser logs."

How the skill works

The SKILL.md is organized around a decision tree: Claude first chooses the right approach for the task (static HTML vs a running dev server vs an already-running app), then applies a reconnaissance-then-action pattern - discover elements and state first, act second. It also documents the most common pitfall (acting on elements before the page settles) and a set of best practices for stable automation.

The centerpiece utility is scripts/with_server.py, which starts your dev server, waits until it is ready, runs the Playwright interaction, and tears everything down cleanly.

What's inside the skill folder

• scripts/with_server.py - server lifecycle wrapper for tests
• examples/static_html_automation.py - driving static pages
• examples/element_discovery.py - the reconnaissance pattern in code
• examples/console_logging.py - capturing browser logs
• SKILL.md, LICENSE.txt

Key takeaways for your own skills

• Put decision trees at the top: routing Claude to the right sub-workflow early prevents most tool misuse.
• Worked examples (three runnable scripts) teach faster than API documentation.

See it on GitHub

skills/webapp-testing