Add environment variable setup instructions to README.md

README.md

@@ -11,4 +11,25 @@ license: mit
 short_description: HF Agents Course
 ---
 
-An example chatbot using [Gradio](https://gradio.app), [`huggingface_hub`](https://huggingface.co/docs/huggingface_hub/v0.22.2/en/index), and the [Hugging Face Inference API](https://huggingface.co/docs/api-inference/index).
+
+## Environment Variables
+
+To run this application, you need to set up the following environment variables in a `.env` file:
+
+```
+# Hugging Face API token (required)
+HUGGINGFACEHUB_API_TOKEN=your_huggingface_token
+
+# Langfuse logging (optional)
+LANGFUSE_SECRET_KEY=your_langfuse_secret
+LANGFUSE_PUBLIC_KEY=your_langfuse_public
+LANGFUSE_HOST=https://cloud.langfuse.com
+
+# Weather API (required for weather tool)
+WEATHERAPI_KEY=your_weatherapi_key
+```
+
+You can obtain these API keys from:
+- [Hugging Face](https://huggingface.co/settings/tokens)
+- [Langfuse](https://langfuse.com/)
+- [WeatherAPI](https://www.weatherapi.com/)