Xây AI Agent đầu tiên bằng Python

python3 -m venv .venv
source .venv/bin/activate
python3 -m pip install openai

import json
import os

TOOLS = [{"type": "function", "name": "lookup_stock",
    "description": "Read fictional training inventory, never live stock.",
    "strict": True, "parameters": {"type": "object",
    "properties": {"sku": {"type": "string"}},
    "required": ["sku"], "additionalProperties": False}}]

def execute(name, raw):
    if name != "lookup_stock":
        raise ValueError("unknown tool")
    args = json.loads(raw)
    if not isinstance(args, dict) or set(args) != {"sku"}:
        raise ValueError("invalid arguments")
    if not isinstance(args["sku"], str) or not 1 <= len(args["sku"]) <= 40:
        raise ValueError("invalid sku")
    stock = {"DEMO-PEN": 7, "DEMO-BOOK": 0}
    sku = args["sku"]
    return {"sku": sku, "units": stock.get(sku), "found": sku in stock}

def run(client, model, question):
    history = [{"role": "user", "content": question}]
    for turn in range(4):
        response = client.responses.create(model=model, input=history,
            tools=TOOLS, max_output_tokens=500,
            instructions="Use lookup_stock before stating quantities. "
            "Label all inventory as fictional. Unknown means unknown.")
        history.extend(response.output)
        calls = [item for item in response.output if item.type == "function_call"]
        if not calls:
            if not response.output_text.strip():
                raise RuntimeError("no final answer")
            return response.output_text
        if len(calls) > 3:
            raise RuntimeError("too many tool calls")
        for call in calls:
            try:
                result = execute(call.name, call.arguments)
            except (ValueError, TypeError) as error:
                result = {"error": str(error)}
            history.append({"type": "function_call_output",
                "call_id": call.call_id, "output": json.dumps(result)})
    raise RuntimeError("turn limit reached")

if __name__ == "__main__":
    from openai import OpenAI
    client = OpenAI(timeout=20, max_retries=1)
    print(run(client, os.environ["OPENAI_MODEL"],
              "How many DEMO-PEN units are in the training inventory?"))

from agent import execute
assert execute("lookup_stock", '{"sku":"DEMO-PEN"}')["units"] == 7
assert execute("lookup_stock", '{"sku":"MISSING"}')["found"] is False
try:
    execute("delete_all", "{}")
except ValueError:
    pass
else:
    raise AssertionError("unknown tool accepted")
print("executor checks passed")

python3 agent.py