Comparison · both free
Prompt Debugger vs Test Plan from the Prompt
The short answer
Both start from a prompt. The Prompt Debugger fixes a prompt whose answers are wrong. Test Plan from the Prompt reads the prompt you used to build a feature and lists what to test in the code. One fixes the prompt, the other checks what it built.
Prompt Debugger
Paste a prompt that keeps giving you bad answers, plus one bad answer. Get the exact lines causing it and a fixed prompt.
- You paste
- Collect the evidence. Copy the full prompt exactly as the model sees it, including the system prompt and any template variables. Then grab one bad answer. One real failure tells the agent more than a description of it.
- You get
- Fixed prompt. Reader named, friendliness rule cut, JSON schema with one filled example, and a 'no prose outside the JSON' line. Each change tied to a bug.
- When to use it
- Use it when a prompt mostly works but gives the same wrong answer every few runs, and adding IMPORTANT in caps made it worse.
- When to skip it
- It needs at least one real bad answer. Without an example of the failure, it can only give general advice.
- Runs in
- ChatGPT, Claude, Gemini, Cursor
- Difficulty
- Easy
- Shelf
- Learning
Test Plan from the Prompt
Paste the prompt you used to vibe-code a feature. Get the checks to run before merge, including the case that prompt forgot.
- You paste
- Paste the original prompt. Use the prompt you gave the coding agent, not a cleaned-up spec you wrote afterward. The gaps in that prompt are the point.
- You get
- Later. The 7-day boundary and the hidden button are listed as follow-ups, not pretended to be done.
- When to use it
- Use it right after you vibe-code a feature, when the happy path works and the cases you never mentioned are untested.
- When to skip it
- It writes the checks, not the test code. Ask your coding agent to implement the cases once you agree with the list.
- Runs in
- Cursor, Claude, ChatGPT
- Difficulty
- Medium
- Shelf
- Coding & Vibe Coding
Questions
What is the difference between Prompt Debugger and Test Plan from the Prompt?
Both start from a prompt. The Prompt Debugger fixes a prompt whose answers are wrong. Test Plan from the Prompt reads the prompt you used to build a feature and lists what to test in the code. One fixes the prompt, the other checks what it built.
Are Prompt Debugger and Test Plan from the Prompt free?
Yes. Both are free prompts from One Agent a Day under CC BY 4.0. Prompt Debugger runs in ChatGPT, Claude, Gemini, Cursor. Test Plan from the Prompt runs in Cursor, Claude, ChatGPT.
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