Build an agent with tool calling

import json
import os

from openai import OpenAI

client = OpenAI(base_url="https://api.aimodelsrouter.ai/v1", api_key=os.environ["AMR_API_KEY"])
MODEL = "deepseek/deepseek-v4.1-flash-1017"


# 1. Your real functions. The model decides when to call them; your code runs them.
def get_order_status(order_id: str) -> dict:
    return {"order_id": order_id, "status": "processing", "carrier": None}  # replace with a real lookup


def refund_order(order_id: str, reason: str) -> dict:
    return {"order_id": order_id, "refund": "approved", "amount_usd": 49.0}  # replace with a real action


FUNCTIONS = {"get_order_status": get_order_status, "refund_order": refund_order}

# 2. Describe them to the model.
tools = [
    {"type": "function", "function": {
        "name": "get_order_status", "description": "Look up the shipping status of an order.",
        "parameters": {"type": "object", "properties": {"order_id": {"type": "string"}}, "required": ["order_id"]}}},
    {"type": "function", "function": {
        "name": "refund_order", "description": "Refund an order. Only when the customer asks for a refund.",
        "parameters": {"type": "object", "properties": {"order_id": {"type": "string"}, "reason": {"type": "string"}},
                       "required": ["order_id", "reason"]}}},
]

# 3. The agent loop: call the model, run the tools it asks for, send back the results, repeat.
messages = [{"role": "user", "content": "Where is my order 1042? If it hasn't shipped yet, refund it."}]
for _ in range(10):  # safety limit on steps
    response = client.chat.completions.create(model=MODEL, messages=messages, tools=tools)
    message = response.choices[0].message
    if not message.tool_calls:
        print(message.content)
        break
    messages.append(message.model_dump(exclude_none=True))
    for call in message.tool_calls:
        result = FUNCTIONS[call.function.name](**json.loads(call.function.arguments))
        print(f"-> {call.function.name}({call.function.arguments}) = {result}")
        messages.append({"role": "tool", "tool_call_id": call.id, "content": json.dumps(result)})