from pydantic import BaseModel, EmailStr, Field
from langchain.agents import create_agent
from langchain.agents.structured_output import ToolStrategy
from langchain_openai import ChatOpenAI


class ContactInfo(BaseModel):
    """Contact details extracted from a message."""

    name: str = Field(description="The person's full name")
    email: EmailStr = Field(description="The person's email address")
    phone: str = Field(description="The person's phone number")


model = ChatOpenAI(model="gpt-5-nano")

agent = create_agent(
    model=model,
    tools=[],
    response_format=ToolStrategy(ContactInfo),
)

result = agent.invoke(
    {
        "messages": [
            {
                "role": "user",
                "content": (
                    "Extract contact details for Jane Doe, "
                    "jane.doe@example.com, +1-202-555-0147."
                ),
            }
        ]
    }
)

contact = result["structured_response"]
print(type(contact).__name__)
print(contact.model_dump_json(indent=2))