Promptles
Errors & Proof

Ask Claude to Verify Its Work

End with a check: have Claude run it and show you the result, so done means proven, not claimed.

Claude can run your tests, scripts, and the app itself, so ask it to prove the change works and show you the result. Name the check that would convince you: a test run, the script on a sample, a screenshot. Vague: "Fix the date parsing." Specific: "Fix the date parsing, then run it on the three dates from the bug report and show me what each one becomes."

Where you'll practice this

5 Promptles scenarios teach this principle directly. Each one drops you into a real engineering ticket and asks you to write the prompt you'd send to Claude Code.

  • Verify the Whole Chain Before It Ships

    Every Friday, Claude assembles Wrenfield's update for Northwind: headline numbers from a Drive sheet, a summary of open Linear issues, then a post to #northwind-client, the Slack channel Northwind's team reads. It runs end to end with nobody checking. Last month's post, and the…

  • Prove It Works

    `kettle`, the team's ops CLI (a tool you run by typing commands in the terminal), is getting a `--timeout` flag. It needs a `parseDuration` helper that turns text like `1h30m`, `45s`, or `2h` into seconds, and `90m` has to work too. In kettle, a timeout of 0 means "wait…

  • Prove the Pagination Fix

    Customers paging through search results on the Copper Kettle shop sometimes see the same product twice and never see others. Hana noticed it only happens among the 40 products from last spring's bulk import, which all share the same added-at time. Claude changed the shared…

  • Test, Then Save Your Progress

    Adding, ticking, and counting all work now. Ines set the project up with git (a tool that saves snapshots of your project), moved the counting code into `count.js`, and added a small test in `test.js` that checks it. You've never saved a snapshot. In git, each one is a commit…

  • Try It Before You Ship

    All four parts of shipkit are built: the `notes` skill, the `changelog-style` skill, the lint hook, and the `github` MCP server. Dana is about to set the version to 1.0.0 and tag the release, and then Priya will tell all 12 engineers to install it. Each part was tested alone at…

Other principles in Errors & Proof