langchain-evolution-deck/examples/slide-019/script.py

"""
Slide 19: @tool -- любая функция становится инструментом
Section 1: LangChain 1.0
Source: slides/section1-chains/slide-19.js

Сгенерировано автоматически из slide-NN.js / sectionN.pptx.
Паттерн провайдера скопирован из
bro-js/agents/teacher/assistant/src/angry_teacher/llm.py.

Запуск:
  cd langchain-evolution-deck
  cp .env.example .env   # заполни OPENAI_API_KEY
  python examples/slide-019/script.py
"""
import os
from dotenv import load_dotenv
from langchain_openai import ChatOpenAI

load_dotenv()

llm = ChatOpenAI(
    # model="openrouter/free",
    # model="qwen/qwen3.5-35b-a3b",
    model="openai/gpt-oss-20b",
    # model="nvidia/nemotron-3-nano",
    # model="qwen/qwen3.5-9b",
    base_url="https://llm.brojs.ru/v1",
    # base_url="https://api.minimax.io/v1",
    # base_url="http://0.0.0.0:8090/v1",
    # base_url="https://openrouter.ai/api/v1",
    # api_key=os.getenv("MINIMAX_API_KEY"),
    api_key=(os.getenv("OPENAI_API_KEY") or "").strip() or None,
    temperature=0.7,
    stream_usage=True,
)


# === Code from slide 19 ===
from langchain.tools import tool
from langchain.chat_models import init_chat_model

@tool
def get_weather(city: str) -> str:
    """Get the current weather for a given city."""
    return f"Sunny, 22C in {city}"

@tool
def search_docs(query: str, top_k: int = 3) -> list[str]:
    """Search internal documentation. Returns top_k snippets."""
    return [f"doc about {query} #{i}" for i in range(top_k)]

# bind_tools -- модель знает, какие функции можно вызвать
model = init_chat_model("openai:gpt-4.1-mini")
bound = model.bind_tools([get_weather, search_docs])

result = bound.invoke("What is the weather in Paris?")
print(result.tool_calls)
# [{"name": "get_weather", "args": {"city": "Paris"}, "id": "..."}]