Pydantic AI

Pydantic AI is a Python agent framework designed to make it easy to build production grade applications with AI. This guide demonstrates how to integrate Vercel AI Gateway with Pydantic AI to access various AI models and providers.

1. Create a new project

   First, create a new directory for your project and initialize it:

   terminal

   mkdir pydantic-ai-gateway
   cd pydantic-ai-gateway

2. Install dependencies

   Install the required Pydantic AI packages along with the python-dotenv package:

   terminal

   pip install pydantic-ai python-dotenv

3. Configure environment variables

   Create a .env file with your Vercel AI Gateway API key:

   .env

   VERCEL_AI_GATEWAY_API_KEY=your-api-key-here

   If you're using the AI Gateway from within a Vercel deployment, you can also use the VERCEL_OIDC_TOKEN environment variable which will be automatically provided.

4. Create your Pydantic AI application

   Create a new file called main.py with the following code:

   main.py

   from dotenv import load_dotenv
   from pydantic import BaseModel
   from pydantic_ai import Agent
   from pydantic_ai.models.openai import OpenAIModel
   from pydantic_ai.providers.vercel import VercelProvider
    
   load_dotenv()
    
   class CityInfo(BaseModel):
       city: str
       country: str
       population: int
       famous_for: str
    
   agent = Agent(
       OpenAIModel('anthropic/claude-opus-4.6', provider=VercelProvider()),
       output_type=CityInfo,
       system_prompt='Provide accurate city information.'
   )
    
   if __name__ == '__main__':
       cities = ["Tokyo", "Paris", "New York"]
    
       for city in cities:
           result = agent.run_sync(f'Tell me about {city}')
           info = result.output
    
           print(f"City: {info.city}")
           print(f"Country: {info.country}")
           print(f"Population: {info.population:,}")
           print(f"Famous for: {info.famous_for}")
           print("-" * 5)

   The following code:

   • Defines a CityInfo Pydantic model for structured output
   • Uses the VercelProvider to route requests through the AI Gateway
   • Handles the response data using Pydantic's type validation

5. Running the application

   Run your application using Python:

   terminal

   python main.py

   You should see structured city information for Tokyo, Paris, and New York displayed in your console.