LangChain

pip install langchain langchain-openai

import os

from langchain_openai import ChatOpenAI

llm = ChatOpenAI(
    model="auto",                              # or any Mesh catalog id
    base_url="https://api.meshapi.ai/v1",
    api_key=os.environ["MESH_API_KEY"],        # rsk_...
)

from langchain_core.messages import HumanMessage, ToolMessage
from langchain_core.tools import tool

BOOK = {"A-1042": {"state": "in transit", "eta_days": 2}}


@tool
def get_shipment_status(order_id: str) -> dict:
    """Look up the shipment status of an order."""
    if order_id in BOOK:
        return {"status": "success", "order_id": order_id, **BOOK[order_id]}
    return {"status": "error", "error_message": f"No order {order_id}."}


llm_with_tools = llm.bind_tools([get_shipment_status])

messages = [HumanMessage("What's the shipment status of order A-1042?")]
first = llm_with_tools.invoke(messages)

messages.append(first)
for call in first.tool_calls:
    result = get_shipment_status.invoke(call["args"])
    messages.append(ToolMessage(content=str(result), tool_call_id=call["id"]))

final = llm_with_tools.invoke(messages)
print(final.content)

from langgraph.prebuilt import create_react_agent

agent = create_react_agent(llm, tools=[get_shipment_status])

result = agent.invoke({"messages": [("user", "Status of order A-1042?")]})
print(result["messages"][-1].content)