Tool Use & Function Calling

tools = [{"type": "function", "function": {
    "name": "get_order",
    "parameters": {"type": "object", "properties": {"order_id": {"type": "string"}}, "required": ["order_id"]},
}}]
response = client.chat.completions.create(model="gpt-4o-mini", messages=messages, tools=tools)

"""tool_use.py - safe tool execution loop."""
from __future__ import annotations
 
import json
from pydantic import BaseModel, ValidationError
from openai import OpenAI
 
client = OpenAI()
 
class GetOrderArgs(BaseModel):
    order_id: str
 
def get_order(order_id: str) -> dict:
    orders = {"ORD-123": {"status": "shipped", "total": 49.99}}
    return orders.get(order_id, {"error": "not found"})
 
TOOL_REGISTRY = {"get_order": (GetOrderArgs, get_order)}
 
tools = [{"type": "function", "function": {
    "name": "get_order",
    "description": "Look up order by ID",
    "parameters": GetOrderArgs.model_json_schema(),
}}]
 
messages = [{"role": "user", "content": "What is the status of order ORD-123?"}]
 
for _ in range(5):
    resp = client.chat.completions.create(model="gpt-4o-mini", messages=messages, tools=tools)
    msg = resp.choices[0].message
    if not msg.tool_calls:
        print(msg.content)
        break
    messages.append(msg)
    for call in msg.tool_calls:
        name = call.function.name
        schema_cls, fn = TOOL_REGISTRY[name]
        try:
            args = schema_cls.model_validate_json(call.function.arguments)
            result = fn(**args.model_dump())
        except ValidationError as e:
            result = {"error": str(e)}
        messages.append({"role": "tool", "tool_call_id": call.id, "content": json.dumps(result)})