Building AI Agents That Actually Work

The problem with most AI agents

Everyone's building AI agents right now. Most of them don't work well. Not because the technology isn't ready, but because builders are making the same mistakes over and over.

The number one mistake: trying to make the agent too general-purpose. An agent that can "do anything" usually does nothing reliably.

What makes a good agent

The best AI agents I've built share three characteristics:

1. Narrow scope. They do one thing exceptionally well rather than many things poorly.
2. Clear guardrails. They know when to act and when to escalate to a human.
3. Observable behaviour. You can see exactly what the agent did and why.

The architecture that works

After building agents across industries (from fitness coaching to recruitment automation), I've landed on a pattern that consistently delivers:

Define the happy path first

Before writing any code, map out the exact conversation or workflow the agent should handle. Not edge cases. Not error states. Just the golden path.

Build the scaffolding

Set up the tool calls, the prompt structure, and the evaluation framework before you start optimising the prompts. You need to be able to measure improvement before you start chasing it.

Iterate on prompts with real data

Synthetic test cases will only get you so far. The moment you put real user inputs through your agent, you'll discover failure modes you never imagined.

The tools I reach for

• LLM providers. I primarily use Claude and GPT-4 depending on the use case.
• Orchestration. Simple state machines beat complex frameworks for most agents.
• Evaluation. Build a test suite of real inputs and expected outputs early.
• Monitoring. Log every decision the agent makes so you can debug production issues.

Ship it, then improve it

The temptation is to keep refining until it's perfect. Don't. Ship it to a small group, collect real usage data, and iterate. You'll learn more in one week of real usage than a month of testing.

The agents that work aren't the most sophisticated. They're the most focused.