Building an AI Assistant Workflow with Retell.ai, Google Sheets & Google Calendar

In our agency, we specialize in Voice AI solutions. Recently, we built a workflow that integrates Retell.ai (for voice AI intelligence) with Google Sheets and Google Calendar to create a seamless AI assistant that can read data, analyze it, and schedule events automatically.

Here’s a breakdown of how the workflow looks and how each block contributes to the bigger picture:

🔹 1. Manual Trigger – Execute Workflow

The workflow starts when we click Execute workflow. This acts as a manual trigger, ensuring we have control over when to start the process (ideal for testing or on-demand execution).

🔹 2. Get Data from Google Sheets – Get row(s) in sheet

The assistant first reads data from a Google Sheet. Think of this sheet as the “source of truth” where all customer requests, meeting notes, or booking information is stored.

Example: If a client wants to schedule a product demo, their details are logged in the sheet.
This block fetches those rows one by one for processing.

🔹 3. AI Agent – OpenAI Chat Mode + Structured Output Parser

Here’s where the intelligence comes in:

The AI Agent uses OpenAI’s Chat Model to analyze the data from the sheet.
With the Structured Output Parser, the assistant ensures responses are machine-readable (no vague answers, only structured data).

👉 This step is critical because it transforms raw sheet data into meaningful instructions.

🔹 4. API Call – HTTP Request (Retell.ai)

Once the AI processes the data, we call Retell.ai’s API.

This step is where Voice AI magic happens.
Retell.ai takes the structured data and transforms it into voice interactions or further decision-making workflows.

🔹 5. Webhook Entry Point – Webhook

Apart from manual execution, we also enabled Webhook triggers.

External systems (like a CRM or a website form) can send data to this webhook.
The workflow then kicks off automatically, making the AI assistant event-driven.

🔹 6. Conditional Logic – If Block

Not every incoming request needs action.

The If block checks conditions (e.g., “Is this request valid?” or “Does it require a meeting?”).
If true → continue the flow.
If false → end gracefully with a No Operation (do nothing) block.

🔹 7. Responding Back – Respond to Webhook

If conditions are met, the assistant immediately sends a response back to the source system via the webhook. This gives real-time confirmation to the client or system that their request has been received and processed.

🔹 8. Updating Google Sheets – Update row in sheet

Next, the workflow updates the original Google Sheet with the new status.

Example: From “Pending” → “Scheduled”.
This keeps records updated and ensures no duplicate scheduling.

🔹 9. Creating Events – Google Calendar Integration

Finally, the assistant creates a new Google Calendar event.

This could be a client meeting, demo, or consultation.
Everything is logged, and both team members and clients stay in sync without manual entry.

🎯 Why This Matters

This workflow is more than just automation — it’s a Voice AI-powered assistant that:

Reads requests from spreadsheets.
Uses AI to make sense of them.
Talks to Retell.ai for voice intelligence.
Updates records automatically.
Schedules events in Google Calendar.

For agencies like ours, this means less time spent on manual scheduling and more time delivering value to clients.

🚀 What’s Next?

We’re exploring advanced use cases like:

Automatically sending confirmation emails after calendar booking.
Using voice AI for real-time call handling.