Building Your First AI Agent with Python: A Beginner's Guide

AI agents are programs that can perceive information, decide what to do, and take actions toward a goal. Unlike a simple chatbot that only responds to prompts, an agent can use tools, follow steps, and adapt its behavior based on context. In this tutorial, you’ll build a small weather assistant agent in Python that can answer questions like “What’s the weather in Paris?” by calling a weather API.

Prerequisites

Before you start, make sure you have:

• Basic Python knowledge


• Python 3.10+


• An OpenAI API key


• A weather API key (like OpenWeatherMap)


• pip installed

Install the libraries:

1. Understand the agent loop

A simple agent usually follows this pattern:

1. Receive a user request


2. Decide whether a tool is needed


3. Call the tool



4. Use the result to generate a final response




5. Set up your project

Create a file named agent.py and load your environment variables:

1. Build the weather tool

This function calls OpenWeatherMap and returns a simplified result.

1. Let the model decide when to use the tool

We’ll use OpenAI’s API with function calling so the model can request the weather tool.

Conclusion

You just built your first AI agent. Starting with a weather assistant is a great way to learn the workflow without getting overwhelmed. From here, you can expand into more advanced agents with memory and multiple tools.