SDK Overview

uv add cartesia-line

import os
from line.llm_agent import LlmAgent, LlmConfig, end_call
from line.voice_agent_app import VoiceAgentApp

async def get_agent(env, call_request):
    return LlmAgent(
        model="anthropic/claude-haiku-4-5-20251001",
        api_key=os.getenv("ANTHROPIC_API_KEY"),
        tools=[end_call],
        config=LlmConfig(
            system_prompt="You are a helpful assistant.",
            introduction="Hello! How can I help you today?",
        ),
    )

app = VoiceAgentApp(get_agent=get_agent)

from typing import Annotated
from line.llm_agent import loopback_tool

@loopback_tool
async def get_order_status(ctx, order_id: Annotated[str, "The order ID"]):
    """Look up an order's current status."""
    order = await db.get_order(order_id)
    return f"Order {order_id} is {order.status}"

from line.llm_agent import LlmAgent, LlmConfig, agent_as_handoff, end_call

spanish_agent = LlmAgent(
    model="gpt-5-nano",
    api_key=os.getenv("OPENAI_API_KEY"),
    tools=[end_call],
    config=LlmConfig(
        system_prompt="You speak only in Spanish.",
        introduction="¡Hola! ¿Cómo puedo ayudarte?",
    ),
)

main_agent = LlmAgent(
    model="anthropic/claude-haiku-4-5-20251001",
    api_key=os.getenv("ANTHROPIC_API_KEY"),
    tools=[
        end_call,
        agent_as_handoff(
            spanish_agent,
            name="transfer_to_spanish",
            description="Transfer when user requests Spanish.",
        ),
    ],
    config=LlmConfig(...),
)

from line.llm_agent import end_call, web_search

agent = LlmAgent(
    tools=[end_call, web_search],  # Add built-in web search
    ...
)