1. Introduction

This tutorial will walk you through the process of building an Express Agent. You can find the full code in the demo/express folder.

We will:

• Create a workflow with a basic tool-calling agent loop.
• Add state to the workflow, so that we can track the state of the agent.
• Add human-in-the-loop to the workflow. Some tools are important enough that we want to ask a human to confirm and review actions.
• Deploy the workflow to a simple express server.

Prerequisites

• Basic knowledge of TypeScript and Node.js.
• Basic knowledge of the command line.
• An OpenAI API key or OpenAI-compatible service

Setup

To run the examples, create a new folder and then type the following commands to initialize a new project and to install the required dependencies:

npm init
npm pkg set type=module # Make sure we're using ESM modules
npm add @llamaindex/workflow-core@^1.3.1 express@^5.1.0 openai@^5.7.0 uuid@^11.1.0
npm add -D @types/express@^5.0.0 tsx@^4.20.4

As we’re adding tsx to the project, you can run any example file just by typing: npm run tsx <filename>.