thinkhard.SI
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Prompt Grader

How good is your prompt

Paste what you would type into ChatGPT, Claude or Gemini. You get a score out of 10 straight away, then a few plain questions that turn it into a better prompt. Free, and nothing you type leaves this page.

AI settings
How hard should it think?

The score and the questions run in this page. Improve with AI sends your prompt from this browser straight to the AI company you choose, with your own key. thinkhard.si never sees it.

Your reviewed prompts

Kept in this browser only. Reopen one to fill its blanks, improve it again or test it.

How it works

The score is a count, not an opinion. Your prompt meets ten checks, and each one it covers adds a point. Ten out of ten means the AI has nothing left to guess.

What happens to your prompt
  1. Free, in your browser. Score and questionsSimple rules score your wording as you type. Each gap becomes a question, and your answers build a better prompt on the spot.Instant
  2. With your key, straight to the AI company you choose. At the same time
    AI reviewOne AI reads your prompt for meaning and says what it thinks you want.
    New versionA second AI rewrites it with your answers, leaving a blank wherever only you know the detail.
    About 10 seconds
  3. With your key, straight to the AI company you choose. CheckThe new version goes back to the reviewer, which never saw the rewriter's thinking. Nobody marks their own work.A few seconds
  4. With your key, straight to the AI company you choose. Test bothIf you like, both versions run, and a judge that cannot tell which is which picks the better answer.Optional

Fast is the default. Careful lets the rewriter think longer, and Thorough sends anything still missing back for a second pass.

The ten checks, in one prompt
Example prompt

Task:10 Write a launch email1 for existing customers of our invoicing app, who read email on their phones and give it ten seconds2. Background:10 The feature is Auto-reminders. It chases late payments for them and goes live today.3 Requirements:10 Under 120 words4, as a subject line, a preview line and three short paragraphs5. No exclamation marks, and no talk of AI6. A good email earns a click on Try it from someone who reads only the first line7. If a detail is missing, leave a note in brackets instead of guessing9. Example:10 Match the tone of last month's email, pasted below.8

  1. 1What to makeSays exactly what to produce.
  2. 2Who it's forNames the reader and how they will use it.
  3. 3Background factsGives the facts the AI cannot guess.
  4. 4LengthSets the size: words, items, pages or time.
  5. 5FormatSays what shape the answer takes.
  6. 6What to avoidRules out what you do not want.
  7. 7What good looks likeDescribes a good result.
  8. 8An exampleGives a sample to match.
  9. 9If unsureSays what to do when something is missing.
  10. 10LayoutLabeled sections, the way the AI reads best.

A check counts only when the prompt itself says it. A check that cannot matter for the request does not count against it, and a blank such as [AUDIENCE] counts as covered, because you fill it in before sending.

One prompt at every score

Pick a score. Each step adds the one sentence that covers the next check, and the crystal grows to match. The scores borrow the Mohs scale of mineral hardness, from talc at 1 to diamond at 10.

The grains coarsen and brighten as hardness rises. A petrographer will object that real diamond is isotropic and would sit black between crossed polars. We took the liberty.

Laid out for your AI

AI tools do not read alike. Each column is the order the company behind it recommends; pick one to see the rules the rewrite follows and the tenth check looks for.

Questions

Do I need an API key?
No. The score and the questions are free and work without one. A key is only for Improve with AI, which sends your prompt to an AI company to review and rewrite. Google, Groq and OpenRouter give free keys, and Settings explains how in about two minutes.
Does my prompt go to thinkhard.si?
No. The score and the questions run inside this page. Improve with AI goes from your browser straight to the AI company you pick, with your own key. Reviews are kept in this browser only, and a shared link carries the prompt inside the link itself.
What does Improve with AI cost?
Nothing to thinkhard.si. The AI company bills your key for three short calls, usually well under a cent, and every review shows what it cost. Free keys work here.
Why does the new version have blanks?
The rewriter is told never to make up facts about you. Where a detail only you know is missing, such as your company's name, it leaves a blank and asks you. Answer the questions first and there are fewer blanks.
Is the free score the same as the AI review?
No. The free score looks for telltale words, so it can be fooled in both directions. The AI review reads for meaning. Use the free score to see what is plainly missing while you write.
Can the score be wrong?
Yes. Scores and rewrites come from rules and AI, and both can be wrong. Test both versions for real evidence; the score is a guide.