Skill · Prompt

Diagnose From the Symptom, Not the Guess

A prompt that forces a real diagnosis before a single line of fix.

TypePrompt

Something's broken. You describe it; the agent immediately proposes a fix. You try it — still broken. It proposes a different fix. Still broken. Forty minutes in, you have four patches, three new quirks, and the original bug — because nobody ever stopped to look at what was actually failing.

Every one of those patches was aimed at a guess. The agent pattern-matched your description to a plausible cause and changed code to fix that imagined cause — never the real one. A diagnosis takes effort and a guess is free, so it reaches for the guess. This prompt makes it earn the fix:

✕ Without the prompt

Hears the description, patches the likely cause

▼

Still broken → patches again → again

▼

Four patches, new quirks, original bug intact

✓ With the prompt

Reproduces the symptom, reads the real output

▼

Names the root cause and the evidence for it

▼

One fix, aimed at the actual cause

Paste it when something is failing and you want the cause, not a lottery. Its sharpest moment is the second "still broken" — that sentence is information: it means the diagnosis was wrong, not the patch under-applied. The prompt turns it into a re-read of the new output instead of another roll of the dice.

Paste into the chat

Before proposing any fix, diagnose first:
1. Reproduce the symptom and paste the actual error or wrong output — the real text, not a paraphrase.
2. Trace it to a root cause. State the cause and the specific evidence that points to it.
3. Only then propose the smallest change that addresses that cause.
If I say it's still broken, do not try a different patch — re-read the new output and re-diagnose. A second failed fix means the first diagnosis was wrong.

Prefer your agent install it?

Add this rule to my CLAUDE.md, verbatim:

Before proposing any fix, diagnose first:
1. Reproduce the symptom and paste the actual error or wrong output — the real text, not a paraphrase.
2. Trace it to a root cause. State the cause and the specific evidence that points to it.
3. Only then propose the smallest change that addresses that cause.
If I say it's still broken, do not try a different patch — re-read the new output and re-diagnose. A second failed fix means the first diagnosis was wrong.

Did this help?

Tags#debugging #verify #skill

Other skills

01Verify Before You Call It Done 02Plan First, Then Code 03Map the Blast Radius Before You Edit 04If It's Deterministic, Don't Make It Guess 06Make It Argue Against Its Own Plan 07Hand Off to Your Next Session 08A Review That Doesn't Rubber-Stamp 09Run to the gate, then stop — not step-by-step 10A CLAUDE.md skeleton — turn a description into operating law 11The weekly review prompt — five minutes that turn experience into skill 12Split the work into focused slices, each with clean context 13Is this even worth an agent — ask before you open the chat 14Probe with a small task before you trust it in a new domain

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✕ Without the prompt

✓ With the prompt

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