Tool Status

API Reference

useToolArgsStatus

Reads whether each argument field for the current tool-call message part is still streaming or complete.

Use inside a tool-call renderer to avoid showing incomplete argument values as final.

function WeatherToolUI({
  args,
}: ToolCallMessagePartProps<{ city: string }>) {
  const { propStatus } = useToolArgsStatus<{ city: string }>();

  return (
    <span>
      {propStatus.city === "streaming" ? "Reading city..." : args.city}
    </span>
  );
}

const useToolArgsStatus: <TArgs extends Record<string, unknown> = Record<string, unknown>>() => ToolArgsStatus<TArgs>;

useToolCallElapsed

Hook that returns the elapsed wall-clock time of the current tool call in milliseconds, ticking once per second while the call runs.

Reads part.timing. Returns undefined when the part is not a tool call, carries no timing, ended without a recorded completion (the duration is unknown), or when no message part scope is available (so kit components stay renderable standalone, e.g. in docs previews).

function ToolDuration() {
  const elapsedMs = useToolCallElapsed();
  if (elapsedMs === undefined) return null;
  return <span>{(elapsedMs / 1000).toFixed(1)}s</span>;
}

const useToolCallElapsed: () => number;