# How to Build an AI Agent

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## Table of contents

- What are AI agents?
- Do you even need an AI agent?
- How to build an AI agent
- Best practices for building an effective AI agent
- Takeaways

From automated assistants that guide new users through apps to support bots that resolve queries in seconds, every business today either already has or is building its own AI agent to work smarter and make its product more appealing. But it’s not just the companies driving this change. Users now expect it you to have AI-powered features or AI agents integrated into your product in some way or the other.

So if you're not already on the AI agent bandwagon, you're going to feel the gap sooner than you think. But the good news is that it isn’t too late. You just need to ask the right question - How do you build an AI agent that works?

In this guide, we'll take you through the steps you need to follow to build your very own AI agent.

## What are AI agents?

**AI agents are programs that use machine learnng and artificial intelligence to make decisions and perform tasks on their own using data and logic.**

What makes them different from regular automation is their ability to understand context, adapt as they learn, and respond more intelligently over time. Over and above following a script, [AI agents](https://www.mailmodo.com/guides/ai-agent-builder/) tend to use the information fed into them to actively figure things out and help you complete your workflows and tasks.

## Do you even need an AI agent?

Not every problem requires an AI specific solution, and therefore, not every team needs to build an agent from day one. However, if you are looking to scale your [SaaS workflows](https://www.mailmodo.com/guides/saas-management-software/), hitting bottlenecks that slow down your operations, or your user experience feels clunky, it might be time to [consider using an AI agent](https://unity-connect.com/services/ai-agents/).

Here are some tell-tale signs that an AI agent could actually help your business:

 - **You're buried in repetitive tasks**: If your team is constantly answering the same questions, chasing the same follow-ups, or manually routing requests, an AI agent can step in and take over that.
 - **You want to personalize at scale**: If you have a huge customer base and want to truly personalize your communications, AI agents can adapt their responses based on who they’re talking to. So whether it’s [onboarding](https://www.mailmodo.com/guides/saas-onboarding-software/) new users or following up with leads, they make each interaction feel more relevant without adding more to your plate.
 - **You need faster, sharper decisions**: If processes or decision-making take time, AI agents can sift through data, summarize insights, and even flag issues in real time, helping you make decisions quicker and more confidently.
 - **You’re aiming for consistency**: If there’s inconsistency in your processes, communications or customer experiences and you want to make them consistent, AI agents can help you there. They don’t forget steps, miss details, or drop the ball during handovers. They run 24/7 and provide consistent output, reducing errors and delays.

## How to build an AI agent

So you've figured out whether or not you need an AI agent - great. Now let’s talk about how to build one. There are two paths you can choose from:

 - **Use an AI agent builder**: This is the fastest and easiest route. Tools like Relevance AI or Gumloop offer visual workflow design, built‑in memory and logic modules, and integrations ready to go. Within minutes you can wire up your agent, test it, and deploy it.
 - **Build your AI agent from scratch**:  If you want more control or flexibility, you can also create an agent manually. We’ll walk you through that process. We’ll try and build an AI agent for [qualifying leads](https://www.mailmodo.com/guides/marketing-qualified-lead/) on your pricing page and triggering a personalized follow-up sequence via Mailmodo.    

Before diving in, remember that every agent relies on three core components:

 - **Model**: the LLM doing the reasoning.
 - **Tools**: external APIs/functions enabling action.
 - **Instructions**: clear guidelines that steer behavior
    
Now, let’s get started:

### Step 1: Define the agent’s role

You need to write a crisp prompt that outlines purpose, behavior, and output when defining the role of your AI agent. For example: “You’re a lead qualification assistant on our pricing page. Ask users about budget, intent, and fit. If they qualify, send their details to Mailmodo for personalized follow‑up.” This prompt becomes the backbone of your agent’s logic, and you need to keep refining it as you gather real-world use cases.

### Step 2: Choose your model

The next step is to pick a powerful LLM (e.g., GPT‑4). When doing the setup, make sure that your setup allows you to swap or upgrade models, use function calling, and add fallback logic for unclear inputs. OpenAI’s recent Agents SDK even supports built‑in tools like web search, file search, and computer automation.

### Step 3: Add memory & logic

To stay context-aware, your agent needs to have the following:

 - **Memory**: To track chat history and key user data (e.g., name, company size, budget) in systems like Redis or Pinecone.
 - **Logic rules**: For logical reasoning. For example, “If budget > $X and intent is high → qualify”, otherwise ask more questions or pause.
 - **Intent scoring**: Use keyword maps, a simple classifier, or the LLM itself to infer intent.
    

### Step 4: Integrate tools (including Mailmodo)

At this step, you need to enable your agent to take action. You can do this by using APIs. Here, you’re going to using [Mailmodo API](https://www.mailmodo.com/guides/api/) to push qualified leads (name, email, interest) into a campaign. You can also automate follow-up sequences, then track open and click rates to feed insights back into your agent by fetching data from Mailmodo. OpenAI’s tools synergy, like RAG, web search, and file lookup, helps you amplify this step.

### Step 5: Monitor, iterate, optimize

Deploying isn’t the end. In addition to the above, you need to:

 - Test edge cases (e.g., vague answers or spam).
 - Add fallbacks for when users ask unclear or human-level questions.
 - Log conversations and outcomes, then adjust prompts, classifiers, or rules accordingly.
 - Track metrics like qualified leads and downstream conversions to prove ROI. 

## Best practices for building an effective AI agent

Keep these principles in mind to build agents that are useful, reliable, and easy to improve over time:

 - **Start with one clear use case**: Focus on a single, high-impact workflow before expanding. Narrow scope leads to faster iteration and more measurable outcomes.
 - **Account for edge cases**: Design for ambiguity. Plan how your agent should respond to unclear inputs, out-of-scope queries, or unexpected behaviors.
 - **Set safety triggers and boundaries**: Add checks for when to pause, escalate to a human, or stop the workflow, especially for sensitive or high-stakes tasks.
 - **Keep humans in the loop**: Involve human reviewers to validate agent responses, handle exceptions, and refine performance based on real-world feedback.

## Takeaways

AI agents are no longer futuristic - they’re the present and are already reshaping how SaaS companies onboard users, qualify leads, resolve queries, and even plan campaigns. But the best agents aren’t built overnight. They’re shaped over time through clear purpose, the right logic, and real-world feedback. Whether you use a no-code builder or go hands-on from scratch, the key is to start with a focused use case, keep iterating, and connect it to your existing stack where it matters.

## Frequently Asked Questions

### Do I need to be a developer to build AI agents?


No, you don’t have to be a developer to start building AI agents. If you're using an agent builder like Relevance AI or Gumloop, you can create agents through visual workflows—no code required. But if you're building from scratch, you'll need some comfort with APIs and logic flows.


### What’s the first thing I need to define when building an AI agent?


The first thing you need to define when building an AI agent is the agent’s purpose. What task is it solving? Who is it interacting with? What does success look like? A clear objective helps shape the prompt, logic, and integrations.


### Which model should I use for my AI agent?


The model you use for your AI agent depends on the complexity and nature of your use case. GPT-4 is great for multi-turn conversations and nuanced reasoning. If your use case is lightweight, cheaper models like GPT-3.5 may suffice. Use APIs (like OpenAI or Anthropic) that let you experiment and scale.


### How do I give the agent memory and context?


You can store session data (like user inputs, previous answers, or scores) in a memory backend like Redis or Pinecone. This lets the agent recall earlier interactions and behave more naturally.


### How do I test if my agent is working well?


To test if your AI agent is working well, run real-world simulations. Look for how the agent handles edge cases, unclear inputs, or errors. Monitor output quality, handoff success, and downstream metrics (like qualified leads or open rates if integrated with tools like Mailmodo).

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---

**Author: Jacob Bank**

Jacob is the founder/CEO of Relay.app, building an easy-to-use platform that enables everyone to create AI agents. He's a former Google PM Director who led Gmail and Google Calendar, and previously founded Timeful (acquired by Google in 2015). He shares actionable AI tips and offers honest insights into what AI can and can't do today.

