Spreadsheet Sanity Check

When to use it

The user has a table, budget, forecast, quote or model and is about to send it to someone who will trust it. They want the errors found before the reader finds them. The pasted numbers in, a pass or fail per total out, with every flag tied to a cell or row and the corrected figure printed.

Not for building the model, interpreting what the numbers mean for the business, or writing the commentary around them. This is arithmetic and consistency, nothing else.

What it asks you

One message, numbered.

1. The table or model. Paste it as text with its row and column labels. If you can, include the formulas as well as the values (copy the cell showing the formula). Say which cells are inputs and which are calculated, if you know.
2. The units and period for each number column: currency, thousands or units, per month, per quarter, per year.
3. What the sheet is for and who reads it. A budget for the board is checked harder than a working draft.
4. Anything you already suspect is wrong.

If the user pastes values only, every total is recomputed from the visible components and the output says that formula tests (hard-codes, broken links) could not be run. If units are not given, the check still runs, but the unit test is marked "not run" and the output asks for them. Never assume a unit, a period, a growth rate or a missing input. If a component needed for a total is not visible, the total is marked "cannot verify", not pass.

What comes back

Plain text.

SHEET: name or purpose, reader, size (rows and columns checked), what was given (values only, or values and formulas)

RECOMPUTE Label | Sheet figure | Recomputed | Components | Result ... (every total and subtotal)

FLAGS (ranked) 1. Test name. Cell or row. What is wrong. Corrected figure with arithmetic, or the question to ask. 2. ...

CORRECTED CHAIN (if any total changed) Label: was X, now Y, because ... (every total affected, down to the grand total)

HIDDEN ASSUMPTIONS - Where used, what the number is, no source cell

NOT RUN: tests that could not run and why (no formulas given, no units given)

Pass means the components shown add to the total shown. It does not confirm the inputs. Next: one line naming the single most useful next step.

• 00_START_HERE.pdf: the two-minute set-up for each AI.
• 1 - Skill: spreadsheet-sanity-check.zip, one upload to Claude, ChatGPT, Gemini, Grok or Microsoft 365 Copilot. It switches on by itself when this job comes up.
• 2 - Text file for any AI: the same Move as one .txt. Attach it to any chat, on any plan, and type "Follow this file".

It drafts, you read and send. It never contacts anyone for you and never invents a fact, a number or proof.

A Move is a single play. The whole function in a box is an agent pack.