HOW TO TEST MCP APPS FOR ACCESSIBILITY, AND WHY IT MATTERS

Summary from the TLDR Design newsletter

MCP Apps render real UI inside the client instead of leaving presentation to the agent, so that UI must work for everyone. With the testing guide and spec silent on accessibility, a local dev server with a stub host turns each app state into a scannable URL. Common pitfalls include starting headings below h1, mixing host and hardcoded colors, relying on env() for safe-area insets, and keyboard shortcuts that collide with the client's.