Free Lesson
What Is an Agent Harness? Build One From Scratch
60 min
Nov 18, 2026 10:30 AM
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What you'll learn
The 6 parts of an agent harness
Name the tool registry, model, context management, guardrails, loop and verify step, and what each does.
Guardrails the model can't talk its way past
Add iteration and context limits in code, so a confused agent can't run forever or overflow its context.
Verification that catches a lying agent
Check an agent's trace in plain code and let a failed check overrule its claim of success.
Why this topic matters
Most AI agents fail the same way: they report success they did not achieve. Better prompts and bigger models rarely fix it. The harness around the model does. In 1 hour you will watch an agent go from lying about a task to completing it, with the same model and prompt, and leave knowing the 6 parts of a harness and how to add guardrails and verification to your own agents.
