Token Training Booklet

Aisle · Data Prep

How your data is formatted often decides the token bill more than the content itself does. Two tricks that pay off immediately.

Learned ✓

CSV not JSON

Tabular data without repeated key names or nested braces.

Before · pricey

[{"name":"Alice Chen","role":"Engineer","team":"Platform","location":"Berlin"},{"name":"Ben Ortiz","role":"Designer","team":"UX Research","location":"Munich"},{"name":"Priya Nair","role":"PM","team":"Platform","location":"Remote"}]

After · cheap

name,role,team,location
Alice Chen,Engineer,Platform,Berlin
Ben Ortiz,Designer,UX Research,Munich
Priya Nair,PM,Platform,Remote

Every key name ("name", "role" …) gets paid for again on every single line in JSON. CSV states it once, in the header row.

+15 points

Learned ✓

Markdown not HTML

Same structure, no styling tags or attributes that nobody needs to pay for.

Before · pricey

<div class="report"><h2 style="color:#222;font-weight:700;">Q3 Summary</h2><table border="1" cellpadding="4"><tr><th>Metric</th><th>Value</th></tr><tr><td>Revenue</td><td>€120,000</td></tr><tr><td>Churn</td><td>2.1%</td></tr></table></div>

After · cheap

## Q3 Summary

| Metric  | Value    |
|---------|----------|
| Revenue | €120,000 |
| Churn   | 2.1%     |

Divs, classes, and inline styles carry no content of their own — they just cost tokens without helping the model understand anything more.

+15 points

Quick check

You need to hand a model a list of 200 products with four fields (name, price, category, stock). Which format is the cheapest?

Aisle · Workflow

It's not just the data that costs tokens — how you ask, and what you attach, matters too.

Learned ✓

Direct not conversational

Say the task. The model doesn't need the pleasantries.

Before · pricey

Hi there! I hope you're doing well. Could you possibly help me out with something when you get a chance? I'm having a bit of trouble with a function in my code and I'd really appreciate it if you could take a look and let me know what you think might be causing the issue. Thanks so much in advance, I really appreciate your help!

After · cheap

Fix: getUserTotal() returns NaN when cart is empty. Function and error below.

Pleasantries barely change answer quality, but they add up to real cost across hundreds of requests.

+15 points

Learned ✓

One function not one file

Paste only what's broken, plus the error — not the whole codebase.

Before · pricey

import { db } from './db';
import { logger } from './logger';

export function getUser(id) { return db.users.find(u => u.id === id); }
export function createUser(data) { return db.users.insert(data); }
export function deleteUser(id) { return db.users.remove(id); }
export function updateUser(id, data) { return db.users.update(id, data); }
export function getUserTotal(cart) {
  return cart.items.reduce((sum, item) => sum + item.price, 0) / cart.items.length;
}
export function applyDiscount(total, code) { return total * 0.9; }
export function formatCurrency(n) { return `€${n.toFixed(2)}`; }

After · cheap

function getUserTotal(cart) {
  return cart.items.reduce((sum, item) => sum + item.price, 0) / cart.items.length;
}
// Error: Division by zero when cart.items is empty -> returns NaN

Seven unused functions add no context when the bug lives in exactly one of them.

+15 points

Learned ✓

Reset the thread

Every turn resends the whole conversation so far. A fresh chat per task caps what gets resent, instead of it growing all session long.

One long thread — turn 1turn 10

Reset every 3 turns — turn 1turn 10

Illustrative pattern, not measured data.

Without a reset, the resent history grows linearly with every turn. With a regular reset, it stays capped.

+15 points

Quick check

You ask: "Why does this one line in checkout.js throw an error?" What should you attach?

Aisle · Iterative Refinement

When you're iterating repeatedly, a single trick accounts for most of the cost.

Learned ✓

Diff not full rewrite

Ask for the changed lines — don't pay to get the whole file back.

Before · pricey

import { db } from './db';
import { logger } from './logger';

export function getUser(id) { return db.users.find(u => u.id === id); }
export function createUser(data) { return db.users.insert(data); }
export function deleteUser(id) { return db.users.remove(id); }
export function updateUser(id, data) { return db.users.update(id, data); }
export function getUserTotal(cart) {
  if (cart.items.length === 0) return 0;
  return cart.items.reduce((sum, item) => sum + item.price, 0) / cart.items.length;
}
export function applyDiscount(total, code) { return total * 0.9; }
export function formatCurrency(n) { return `€${n.toFixed(2)}`; }

After · cheap

@@ getUserTotal @@
- return cart.items.reduce((sum, item) => sum + item.price, 0) / cart.items.length;
+ if (cart.items.length === 0) return 0;
+ return cart.items.reduce((sum, item) => sum + item.price, 0) / cart.items.length;

For a one-line change, nine out of ten lines of the full file are pure repetition — paid-for repetition.

+15 points

Quick check

You had a 300-line function generated and just want to change one condition. What do you ask for?

＋

Bonus Locker

Five small habits that pay off fast. 2 points each, no before/after needed — just check them off as you apply them.

OCR screenshots instead of uploading images

Strip headers, footers & navigation before pasting

Reuse a tight prompt template instead of rewriting instructions

Break a big ask into smaller, chained steps

Summarize decisions instead of re-pasting the whole history

Aisle · Data Prep

CSV not JSON

Markdown not HTML

Aisle · Workflow

Direct not conversational

One function not one file

Reset the thread

Aisle · Iterative Refinement

Diff not full rewrite

Bonus Locker

Training Receipt