The setup

There are three pieces: the workbook, a Claude project, and the instructions inside it. Everything important lives in the workbook. The project is just where Claude keeps your rules so you don't repeat them every chat.

1. The workbook

Download it from the box on the guide's front page. Open Settings first and fill in three things:

• Fees for the platforms you sell on. eBay is filled in with the rate from its fee page on the date in "Checked on". Look the others up on each platform's own fee page. Fill in the date you checked.
• Your minimum profit per item. The number below which an item isn't worth the photos, listing and trip to the post office. Ten dollars is a starting point, not advice.
• Shipping supplies per item. Mailer, tape, label. It's small, and it adds up.

Then delete the grey example rows. Chapter 2 walks through every tab.

If you'd rather work in Google Sheets, upload the .xlsx to Google Drive and open it with Sheets. The dropdowns and formulas carry over.

2. A Claude project

Make one project called something like "Resale". Projects work on every plan, including Free, which allows up to five. A project holds instructions that apply to every chat in it, and files Claude can refer to.

Add to the project's files:

• The Grades tab, as text or a screenshot, so "B" means the same to Claude as it does to you.
• A short note on what you sell: categories, the brands you know well, the ones you avoid, where you sell. A paragraph is plenty.

Don't upload the whole workbook as a project file. It changes every day, and a stale copy in the project is how Claude ends up quoting last month's numbers. Chapter 2 covers how Claude reads the live sheet.

3. The instructions

Paste this into the project's instructions and edit the bits in brackets:

I resell secondhand goods, mostly [categories], on [platforms]. You help me research prices, decide what to buy, draft listings and review my inventory.

Pricing rules:
- Price only from comps I give you or that you can link to. Never state a price from memory. If you have no comps, say so and tell me what to search for.
- Sold listings are prices. Active listings are hopes. Keep them apart, and say which is which.
- A comp only counts if it's the same item: same model, size, material and similar condition. Tell me what's different about each one.
- Use the median of matching sold comps, not the average, when there are five or more. Show the comps you used.
- Fees and my minimum profit are in the Settings tab of my workbook. Use those numbers, not ones you remember.

Condition grades are A, B, C, D and F, as defined in the Grades file.

When you write a listing, describe only what's in the photos or what I've told you. If a measurement, material or model number isn't known, leave a [check] placeholder instead of guessing.

Dates as YYYY-MM-DD. Money as plain numbers.

4. Settings worth turning on

• Web search lets Claude look things up and link what it found. It's on every plan, including Free. Chapter 3 explains why it's useful for identifying items and less useful for sold prices.
• Code execution and file creation ("Create and edit files" in the newer settings) lets Claude read and hand back .xlsx files. It's on every plan, under Settings > Capabilities.
• Google Drive (a connector) lets Claude read the workbook live if you keep it in Google Sheets.

On the phone app, the same project is there. That's where the sourcing check in chapter 5 happens.