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You can invoke Agent Builder agents from your applications using the LangGraph SDK. Agent Builder agents run on Agent Server, so you can use the same API methods as any other LangSmith deployment.

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Prerequisites

pip install langgraph-sdk python-dotenv

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Authentication

To authenticate with your agent’s Agent Builder deployment, provide a LangSmith Personal Access Token (PAT) to the api_key argument when instantiating the LangGraph SDK client, or via the X-API-Key header. If using X-API-Key, you must also set the X-Auth-Scheme header to langsmith-api-key. If the PAT you pass is not tied to the owner of the agent, your request will be rejected with a 404 Not Found error. If the agent you’re trying to invoke is a and you’re not the owner, you can perform all the same operations as you would in the UI (read-only).

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Example

To get your agent’s agent_id and api_url:
  1. Navigate to the agent in Agent Builder.
  2. Click the settings icon in the top right corner.
  3. Click View code snippets to see pre-populated values for your agent.
Copy the code below and replace agent_id and api_url with the values from your agent’s code snippets. Create a .env file in your project root with your Personal Access Token:
.env
LANGGRAPH_API_KEY=your-personal-access-token

import os
from dotenv import load_dotenv
from langgraph_sdk.client import get_client

load_dotenv()

agent_id = "your-agent-id"

# This must be a PAT tied to your LangSmith account
api_key = os.getenv("LANGGRAPH_API_KEY")
api_url = "https://prod-agent-builder-5ccea139413e5ef289ab8e5d04688e11.us.langgraph.app"

client = get_client(
    url=api_url,
    api_key=api_key,
    headers={
        "X-Auth-Scheme": "langsmith-api-key",
    },
)

async def get_assistant(agent_id: str):
    agent = await client.assistants.get(agent_id)
    print(agent)

if __name__ == "__main__":
    import asyncio
    asyncio.run(get_assistant(agent_id))
Use a Personal Access Token (PAT) tied to your LangSmith account. Set the X-Auth-Scheme header to langsmith-api-key for authentication. If you implemented custom authentication, pass the user’s token in headers so the agent can use user-scoped tools. See Add custom authentication.
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