AIMessage

// Define typed tool calls as a discriminated union
type MyToolCalls =
  | { name: "get_weather"; args: { location: string }; id?: string }
  | { name: "search"; args: { query: string; limit?: number }; id?: string };

// Use with AIMessage
const message: AIMessage<MyToolCalls> = ...;

// Now tool.name === "get_weather" narrows tool.args type
if (message.tool_calls) {
  for (const tool of message.tool_calls) {
    if (tool.name === "get_weather") {
      // tool.args is now { location: string }
      console.log(tool.args.location);
    }
  }
}