Claude CoworkLesson 7

Tips & Best Practices

Cowork runs multi-step jobs on your files. Name files, show examples, and follow up when output needs changes.

Prompting practices that improve Cowork results

🎯
Be specific

Name files, folders, output format, and what done looks like.

✓✗
Show examples

Include one good output sample and one thing to avoid.

🔢
Plan before running

Ask Claude to show its plan before acting — especially for multi-file jobs.

📦
Split large tasks

One prompt per phase: extract → merge → validate.

↩️
Follow up

Refine results in the same project instead of re-running everything.

Write clear, specific prompts

Cowork needs the same details you would give a colleague: which files, what to change, where to save, and how to know the task is finished.

Vague
"Fix my spreadsheet."
No file names, no action, no output
Specific
"Open Q3-expenses.xlsx, add a Vendor column from vendor-list.csv (match on receipt ID), and save as Q3-final.xlsx in the same folder."
Files, action, mapping rule, and save location
Claude Desktop — Cowork · Project: Q3 Expense Reports
Your prompt
"Open Q3-expenses.xlsx, add a Vendor column from vendor-list.csv (match on receipt ID), and save as Q3-final.xlsx in the same folder."
Claude's plan
1.Read vendor-list.csv and Q3-expenses.xlsx
2.Match receipt IDs and fill Vendor column
3.Save as Q3-final.xlsx
A clear Cowork prompt names files, actions, and output — Claude shows its plan before running

Use positive and negative examples

A single sample of correct output — plus one thing to exclude — removes ambiguity faster than a long list of rules. Reference an existing file when you have a format to match.

Positive and negative examples in a prompt
"Summarize each receipt in receipts/. Write one bullet per file. Do include vendor, date, and total. Do not include line-item detail or personal notes. Match the tone of last-month-summary.md."
Do (positive)
• Acme Corp — Mar 4 — $142.00
• Office Depot — Mar 7 — $38.50
Do not (negative)
Itemized pens, paper…
Note: call Sarah about…
Show Claude what good output looks like and what to leave out
Template: "Do [X]. Do not [Y]. Match the format of [existing-file]." Works well in project instructions and individual task prompts.

Ask Claude to show its plan first

For jobs that touch several files or connectors, ask Claude to outline its plan before executing. You review the steps once instead of undoing a wrong batch edit.

Vague
"Update everything in this project folder."
Specific
"Think step by step: list files in receipts/, extract totals to CSV, then merge into Q3-expenses.xlsx. Show your plan before making changes."
Plan-first wording for multi-file Cowork runs
Claude Desktop — Cowork · Project: Q3 Expense Reports
Your prompt
"Think step by step: list files in receipts/, extract totals to CSV, then merge into Q3-expenses.xlsx. Show your plan before making changes."
Claude's plan
1.Scan receipts/ for PDF and image files
2.Extract vendor, date, total → receipts-summary.csv
3.Append rows to Q3-expenses.xlsx (await approval)
A clear Cowork prompt names files, actions, and output — Claude shows its plan before running

Break complex tasks into smaller prompts

One Cowork run should have one main deliverable. When a workflow has extract, transform, and validate phases, run them as separate prompts inside the same project so each step can be checked before the next starts.

One complex goal → three smaller prompts
Goal: "Process all Q3 receipts into the master spreadsheet with flags"
Prompt 1
List all PDFs in receipts/ and extract vendor + total to a CSV
✓ Complete
Prompt 2
Merge CSV rows into Q3-expenses.xlsx using the template columns
✓ Complete
Prompt 3
Flag any row over $5,000 and write a one-line note in flags.txt
● Running…
Split large Cowork jobs into phases — each prompt has one clear deliverable
1
Extract

Pull raw data from source files into a simple intermediate format (CSV, JSON).

2
Transform

Merge, format, or calculate — using output from step 1 as input.

3
Validate

Flag errors, check totals, or compare against a reference file.

Iterate and ask follow-up questions

Cowork keeps task context inside a project. When output is mostly right, send a short follow-up — fix the three missing vendors, change the date format, re-run only the flagged rows — instead of repeating the full prompt.

Cowork task thread — follow-up prompts refine the result
You
Process receipts/ and update Q3-expenses.xlsx.
Claude
Done — 24 rows added. 3 amounts are missing vendor names.
You
For the 3 missing vendors, check vendor-list.csv and fill them in.
Claude
Updated rows 18, 21, 23. All vendors now match vendor-list.csv.
Iterate on Cowork output — fix gaps with short follow-ups instead of restarting from scratch
Follow-up patterns: "Fix rows 18–20 only." · "Use DD/MM/YYYY instead." · "Re-check against vendor-list.csv." Stay in the same project so Claude retains file and instruction context.

Worked example — all practices together

Monthly expense report in one Cowork project
  1. Specific: "Process all PDFs in receipts/March/."
  2. Examples: "Do: vendor, date, total per bullet. Do not: line items. Match last-month-summary.md."
  3. Step by step: "Show your plan before writing to the spreadsheet."
  4. Split: Prompt 1 — extract to CSV. Prompt 2 — merge into expenses.xlsx.
  5. Follow up: "Three vendors are blank — fill from vendor-list.csv."
Summary:
  • Name files, actions, and outputs — vague prompts produce vague results.
  • Use do / do not examples and reference files to lock in format.
  • Plan first, split phases, and follow up in the same project to refine without restarting.

What's Next

Introduction to Claude Chat — the chat interface for questions, writing, and file uploads.