Compose reply draft in Gmail with OpenAI Assistant

This workflow uses OpenAI Assistant to compose draft replies for labeled email messages. It automatically connects the drafts to Gmail threads. 💡 You can add knowledge base to your OpenAI Assistant and make your reply drafts very customized (e.g. compose response with product information in response to inquiry from customer). 🎬 See this workflow in action in my YouTube video about automating Gmail. How it works? The workflow is triggered at regular intervals (default: every 1 minute – you can change this value) to check for messages with a specific label (e.g., "AI"). The content of the retrieved email message is then forwarded to the OpenAI Assistant node, and a reply draft is generated.

Help me set up the n8n workflow "Compose reply draft in Gmail with OpenAI Assistant" (https://n8n.io/workflows/2198). It uses: HTTP Request, Gmail, Code, OpenAI. Import the template JSON into my n8n instance, list every credential I need to create, and walk me through testing it.