Example: 
## Python:

from google import genai

client = genai.Client(
    api_key="...",
    http_options={
        "headers": {
            "x-goog-api-client": "my-sdk-py/1.23",
        }
    }
)

## JavaScript
import { GoogleGenAI } from '@google/genai';

const ai = new GoogleGenAI({
    apiKey: '...',
    httpOptions: {
        headers: {
            'x-goog-api-client': 'my-sdk-js/1.23'
        }
    }
});

## Direct API
curl https://generativelanguage.googleapis.com/v1beta/models/gemini-2.5-flash:generateContent?key=$GOOGLE_API_KEY \
    -H 'Content-Type: application/json'
    -H 'X-Goog-Api-Client: my-sdk/1.23'
    -d '{...}'