ตัวอย่างบทเรียน

What an AI Agent Harness Is Made Of: Instructions, Tools, Environment, State, Feedback Loops

Five harness engineering subsystems: instructions (AGENTS.md), tools, environment, state and feedback loops. Rollout order, ablation testing of each component's value at a fixed model, and the flow diagram between subsystems.

the five harness subsystems ablation measurement adoption curve

คุณจะเรียนรู้อะไรในบทเรียนนี้

Break your harness down into its five subsystems and identify which one is missing.
Learn to measure the contribution of a specific component using an ablation experiment rather than by eye.
Draw up a prioritised implementation plan based on the returns curve.

จุดเริ่มต้นของบทเรียน

'Just write a longer prompt'

The team spends a week writing a five-page AGENTS.md
The agent still won't run the tests by itself
Every session starts with fixing the environment
It looks like the model's fault — but it isn't

The team decides: since the agent keeps getting things wrong, everything needs describing in more detail — so they spend a week writing a five-page instruction document, listing libraries, tone of voice and the tech lead's favourite patterns. The agent reads it once, and still doesn't run the linter before committing — because it physically can't run the linter: it has no shell access with the right permissions. The problem isn't the length of the prompt. The problem is that instructions are only one of the five subsystems of a harness, and if the other four aren't in place, no amount of text will save you.

Myth: a harness = a prompt file

🤔 Myth / Common confusion: 'I've got a harness' = 'I've got a prompt file'
✅ In reality: a harness is five distinct subsystems, and instructions are just one of them
📌 Remember: a shelf full of recipes is not yet a kitchen

The phrase 'I've got a harness' almost always means 'I've got a prompt file' — an AGENTS.md or a CLAUDE.md of some kind. But that isn't a harness, any more than a fridge full of ingredients is a restaurant. You've got the ingredients, but there's no stove, no knives, no way to taste-check a dish, and no quality-control system. A proper harness is five working parts, and missing any one of them doesn't make things 'a bit worse' — it creates its own distinct, predictable class of failures that will repeat again and again.

A kitchen with five stations

A harness = five subsystems working together
A missing part isn't 'slightly worse' — it's a systematic failure
Next up: one station of this kitchen at a time

Take away just one station from a professional kitchen, and it either never opens or ends up feeding customers on a wing and a prayer. A kitchen has five stations: the recipe shelf, the knife station, the stove, the prep counter, and the pass where quality control happens. It's exactly the same with a harness: instructions, tools, environment, state and feedback only work together, and a weak station can't be made up for by a strong one.

บทเรียนฉบับเต็มใช้ได้เมื่อสมัครสมาชิก

ฉบับเต็มมีสไลด์เพิ่มอีก 19 สไลด์

วิดีโอ สไลด์ทั้งหมด โน้ต แบบทดสอบ AI ติวเตอร์ และการสัมภาษณ์จะเปิดหลังเข้าสู่ระบบและสมัครสมาชิก

เข้าสู่ระบบหรือลงทะเบียน สมัครสมาชิก

เนื้อหาบทเรียน

'Just write a longer prompt'
Myth: a harness = a prompt file
A kitchen with five stations
Stations 1–2: instructions and tools
Stations 3–4: environment and state
Station 5: feedback — the pass
Where to start: 5 → 1 → 4 → 3 → 2
❓ Quick check: which station is your weakest?
💡 Diagnosis: how to tell what's broken
Why different teams all follow the same path
🛠 What this looks like in real teams
How to measure a component's value
A zero drop ≠ 'the component is useless'
Ablation pitfalls: it's not the place to start
Constrain, don't micromanage
A map, not a textbook
Your harness rots just like code
Where an agent's work leaks when one link breaks
Read the diagram as a loop, not a list
30 minutes on the weakest station of your harness
Next up: your first AGENTS.md for a payments backend
A harness is a loop, not a file