Hand Off a Whole Job with Cowork · Lesson 3 of 6

Job one: a monthly report from spreadsheets

20 minutes, plus the time Cowork works on its own. Your first real hand-off, start to finish: copies, brief, plan, run, review.

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A monthly report is the perfect first job. It comes back every month, so the brief pays off again and again. It has clear right answers, so you can check it. And it usually lives in spreadsheets you already have.

Marisol at our fictional Comfort Zone Heating & Cooling spends about two hours on the monthly service report. Today she hands it off.

Good first reports are about operations: calls, jobs, tickets, orders, hours, visits, response times. They come from exports or tracking sheets, and a wrong number is embarrassing but fixable.

Hold off, for now, on reports built from bank statements, payroll or customer financial records. Anthropic's safety page says to be cautious about giving Cowork access to financial documents. Your business may decide later that some of that is fine, with the right plan and settings. Start with something lower stakes.

Never point Cowork at the only copy of a file, or at a live shared drive.

• Create a new folder somewhere easy to find, for example in Documents: Cowork jobs. Inside it, make a folder for this job: Report copies, Sept 2026.
• Copy (don't move) the spreadsheets you need into that folder. Use exports or "Save a copy" if they live in an online system.
• Add one example of a past report you liked.
• Open each copy and delete what the report doesn't need: customer names, phone numbers, addresses, account numbers. Keep the columns that matter (date, call type, tech, time on site).

Anthropic's own safety advice lines up with this: give Claude a dedicated working folder rather than broad access, and keep backups of important files. A folder of copies does both.

Open your report's Hand-Off Brief from Lesson 2. Make sure the inputs list the exact file names now in the folder. Save the brief into the same folder as BRIEF.md (or a Word file, if you prefer).

Marisol's limits section reads:

> - Work only inside "Report copies, Sept 2026." > - Don't change or delete calls.xlsx, techs.xlsx or August-report.docx. Save new files only. > - Don't invent numbers. If something's missing, write [CHECK: what's missing]. > - No customer names, addresses or phone numbers in anything you create. > - Don't send or share anything.

• Open the Claude Desktop app. In the message box, select Cowork (or just use the box, if you have the combined experience).
• Select Work in a folder in the chat bar, and choose Report copies, Sept 2026. Only that folder. Not Documents, not your whole drive.
• Type: "Read BRIEF.md in this folder. Before doing anything, show me your plan in numbered steps and list any questions."
• Read the plan slowly. Look for three things:
• Did it find every input? If it lists two files and you gave it three, stop and fix that.
• Does any step go outside the brief? "Clean up the calls sheet" is a red flag if you said don't change inputs.
• Did it ask your "ask me" questions? If it didn't mention cancelled calls and you said to ask, prompt it.
• Answer its questions. Then say: "Go ahead with the plan."

About the approval setting

Anthropic's help pages describe permission modes. In Manual, which is the default, Claude asks before it takes actions and you choose whether to allow each one. In Auto, Claude keeps working without stopping to ask about each step, while automated safety checks run before each action. There's also a mode that skips both, which Anthropic says to use only when you fully trust every connector and action.

For your first three jobs, stay in Manual. Yes, you'll click "Allow" more often. That's the point. You're learning what Cowork does when it works on a job like yours. Anthropic's safety page says to use manual approval when you're using a tool for the first time or when mistakes would be hard to undo.

This is the habit change. Don't watch every step. Don't jump in to rephrase. Answer its permission requests, and otherwise go do your other work. Come back when it says it's done.

If it stops with a question, answer it in one line and write the answer into your brief too, so next month it won't need to ask.

Open the Review and Release Checklist template and work down the report section. The core checks for any report:

• Totals tie out. Open the workings spreadsheet Cowork saved. Check that the total row count matches the source. If calls.xlsx has 412 rows and the report says 398, find out why. (Maybe it dropped cancelled calls, which is fine if you said so.)
• Spot-check five rows by hand. Pick five random calls from the source and find them in the workings. Right type, right week, right tech?
• Read every formula you rely on. Click the total cells. Is the formula adding the column you think it is, over all the rows?
• Hunt for invented facts. Read the summary paragraph. Every claim ("busier because of the heat wave") must come from the files or from you. If it explains *why*, and you didn't give it a why, cut it.
• Find every [CHECK] note. Fill it in or take the sentence out.
• Check for private details. Search the document for names and phone numbers. There shouldn't be any.

Marisol found one problem: the chart labeled week one as "Aug 31 to Sept 6," splitting a week across two months. She told Cowork, in one sentence, to use calendar days in September only. It fixed the chart. Then she added that rule to her brief.

Here's what makes next month faster. Every correction you made goes into the brief. Marisol's brief now says "Weeks start on the 1st of the month. The last week may be short." Next month, that mistake doesn't happen.

Then a person sends the report. Not Cowork. Marisol attached it to an email to Ray herself.

• Build your working folder of copies, with private details removed.
• Save your finished brief into it.
• Start the Cowork job in Manual mode, pointed at that one folder only.
• Read the plan, answer its questions, and let it work.
• Run the report checks on the Review and Release Checklist.
• Put every fix back into the brief.

Check it worked

• The report and the workings spreadsheet are in the job folder, and the input files are unchanged.
• Your totals tie out to the source, and five spot-checked rows match.
• There are no [CHECK] notes left, no invented reasons, and no customer details.
• Your brief now includes at least one rule you learned from this run.
• A person, not Cowork, sent or shared the finished report.

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Next: turn a page of rough notes into a deck or a document.

→ Lesson 4: Job two: a deck or document from notes

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