Add a sample for @function_tool

Author: AnatoliB

samples-v2/openai_agents/function_app.py

@@ -2,7 +2,7 @@
 import os
 import azure.functions as func
 from openai import AsyncAzureOpenAI
-from agents import Agent, Runner, set_default_openai_client
+from agents import Agent, Runner, set_default_openai_client, function_tool
 from durable_decorators import durable_openai_agent_orchestrator
 from model_activity import create_invoke_model_activity
 from azure.identity import DefaultAzureCredential
@@ -146,6 +146,25 @@ async def get_weather(city: str) -> str:
     return f"Weather in {weather.city}: {weather.temperature_range}, {weather.conditions}"
 
 
+
+@function_tool
+def calculate_circle_area(radius: float) -> float:
+    """Calculate the area of a circle given its radius."""
+    import math
+    return math.pi * radius ** 2
+
+@app.orchestration_trigger(context_name="context")
+@durable_openai_agent_orchestrator
+def math_assistant(context):
+    agent = Agent(
+        name="Math Assistant",
+        instructions="You are a helpful math assistant. Use the available tools to help with calculations.",
+        tools=[calculate_circle_area],
+    )
+    result = Runner.run_sync(agent, input="What is the area of a circle with radius 5?")
+    return result.final_output
+
+
 #region Implementation details
 
 create_invoke_model_activity(app) # TODO: Can we hide this line?