Introduce tool_use_behavior on agents

examples/basic/tools.py

@@ -0,0 +1,34 @@
+import asyncio
+
+from pydantic import BaseModel
+
+from agents import Agent, Runner, function_tool
+
+
+class Weather(BaseModel):
+    city: str
+    temperature_range: str
+    conditions: str
+
+
+@function_tool
+def get_weather(city: str) -> Weather:
+    print("[debug] get_weather called")
+    return Weather(city=city, temperature_range="14-20C", conditions="Sunny with wind.")
+
+
+agent = Agent(
+    name="Hello world",
+    instructions="You are a helpful agent.",
+    tools=[get_weather],
+)
+
+
+async def main():
+    result = await Runner.run(agent, input="What's the weather in Tokyo?")
+    print(result.final_output)
+    # The weather in Tokyo is sunny.
+
+
+if __name__ == "__main__":
+    asyncio.run(main())