Pick the right A2UI atoms and read their real field contracts before composing a UI payload. Use when deciding WHAT to render — searching the A2UI Atomic Catalog's 480 typed UI atoms (charts, gauges, steppers, dashboards, decision trees) for a task, or when a previous attempt to render a payload failed because a field name or atom type was guessed wrong. Not for the render step itself (see the a2ui-compose skill) or for MCP connection setup (see a2ui-mcp).
