How to beginner · 3 min read

How to create an OpenAI assistant

Q: How to create an OpenAI assistant

Use the openai SDK v1+ to create an assistant by calling client.chat.completions.create with a conversational messages array. Initialize the OpenAI client with your API key from os.environ and specify a model like gpt-4o for best results.

Quick answer

Use the openai SDK v1+ to create an assistant by calling client.chat.completions.create with a conversational messages array. Initialize the OpenAI client with your API key from os.environ and specify a model like gpt-4o for best results.

PREREQUISITES

Python 3.8+
OpenAI API key (free tier works)
pip install openai>=1.0

Setup

Install the official openai Python SDK and set your API key as an environment variable.

Run pip install openai>=1.0 to install the SDK.
Export your API key in your shell: export OPENAI_API_KEY='your_api_key_here'.

bash

pip install openai>=1.0

Step by step

This example shows how to create a simple OpenAI assistant that responds to user input using the gpt-4o model.

python

import os
from openai import OpenAI

client = OpenAI(api_key=os.environ["OPENAI_API_KEY"])

messages = [
    {"role": "system", "content": "You are a helpful assistant."},
    {"role": "user", "content": "Hello, who won the World Series in 2023?"}
]

response = client.chat.completions.create(
    model="gpt-4o",
    messages=messages
)

print(response.choices[0].message.content)

output

The Texas Rangers won the 2023 World Series.

Common variations

You can customize your assistant by changing the model, adding more context in the system message, or using streaming responses for real-time output.

Use gpt-4.1 or gpt-4o-mini for different performance/cost tradeoffs.
Implement async calls with asyncio and await if needed.
Use the messages array to maintain conversation history.

Troubleshooting

If you get authentication errors, verify your OPENAI_API_KEY environment variable is set correctly. For rate limit errors, consider retrying with exponential backoff. If the model name is invalid, check the latest supported models in the OpenAI documentation.

✅

Key Takeaways

Always use the official openai SDK v1+ with API keys from environment variables.
Start with the gpt-4o model for a strong assistant baseline.
Use the messages parameter to provide context and maintain conversation state.
Customize the system message to define your assistant's behavior.
Handle errors gracefully by checking API key validity and model availability.

Verified 2026-04 · gpt-4o, gpt-4.1, gpt-4o-mini

Verify ↗