A fact-check custom function for Google Sheets to be used as a bound Apps Script project powered by a Vertex AI agent and Gemini model.
This sample demonstrates how you can use two powerful types of AI resources directly into your Google Sheets spreadsheets
A new tutorial published by Google’s Pierrick Voulet, while ostensibly about creating a fact-checking tool in Google Sheets, offers something more valuable to developers: a clear framework for integrating powerful, multi-step Vertex AI Agents into Google Workspace solutions.
While the example is a FACT_CHECK custom function, the underlying architecture caught my eye as it provides a blueprint for connecting Google Workspace applications with the sophisticated reasoning capabilities of custom AI agents.
The Core Architectural Pattern
The solution uses Google Apps Script as a bridge between the user-facing application (Google Sheets) and the backend AI services on Google Cloud.
When a user calls the custom function, the script authenticates with a service account and makes a call to a deployed Vertex AI Agent. This agent then performs its multi-step reasoning. The result is then optionally passed to a Gemini model for final formatting before being returned to the Sheet.
This pattern is highly adaptable for various use cases, allowing developers to bring advanced Agentic AI into your own solutions.
Key Components for Developers
For developers looking to adapt this framework, the tutorial outlines the essential components:
A configured Google Cloud Project with the Vertex AI API enabled.
A deployed ADK Agent on the Vertex AI Agent Engine.
An Apps Script project using a service account for secure, server-to-server authentication with Google Cloud.
The provided Apps Script code (Code.gs and AiVertex.js) serves as a robust starting point, handling the API calls to both the reasoning agent and a Gemini model for final output formatting.
Ultimately, the fact-checking tool serves as an excellent proof of concept. The true value for the developer community, however, lies in the architectural blueprint it provides. This tutorial offers a clear model for integrating multi-step AI reasoning into Google Workspace add-ons, opening the door to a new class of intelligent applications.
