Generate Content using Pydantic Function Calling

This sample demonstrates how to use Pydantic Function declaration to influence the content generated by Gemini MultiModal

Explore further

For detailed documentation that includes this code sample, see the following:

• Function calling reference

Code sample

Python

Before trying this sample, follow the Python setup instructions in the Vertex AI quickstart using client libraries. For more information, see the Vertex AI Python API reference documentation.

To authenticate to Vertex AI, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

from google import genai
from google.genai.types import GenerateContentConfig, HttpOptions

def get_current_weather(location: str) -> str:
    """Example method. Returns the current weather.

    Args:
        location: The city and state, e.g. San Francisco, CA
    """
    weather_map: dict[str, str] = {
        "Boston, MA": "snowing",
        "San Francisco, CA": "foggy",
        "Seattle, WA": "raining",
        "Austin, TX": "hot",
        "Chicago, IL": "windy",
    }
    return weather_map.get(location, "unknown")

client = genai.Client(http_options=HttpOptions(api_version="v1"))
model_id = "gemini-2.5-flash"

response = client.models.generate_content(
    model=model_id,
    contents="What is the weather like in Boston?",
    config=GenerateContentConfig(
        tools=[get_current_weather],
        temperature=0,
    ),
)

print(response.text)
# Example response:
# The weather in Boston is sunny.

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