Tool Rendering (Reasoning Chain)

Combines visible reasoning steps with sequential tool calls.

• get_weather → custom WeatherCard
• search_flights → custom FlightListCard
• everything else (get_stock_price, roll_dice, …) → branded catch-all renderer (useDefaultRenderTool)

The Python agent emits AG-UI REASONING_MESSAGE_* events (parsed out of <reasoning>...</reasoning> blocks the model emits before each tool call), then loops on tool calls until the agent has its answer.