The Art of Prompt Debugging
When a prompt doesn't work as expected, you need a systematic approach to identify and fix the issue. Random changes rarely work—methodical debugging does.
💡 Debugging Mindset: Treat prompts like code. When they fail, there's a reason. Your job is to find it.
The Debugging Process
1
Reproduce
Confirm the issue happens consistently
→
2
Isolate
Find which component is causing the issue
→
3
Hypothesize
Form theories about why it's failing
→
4
Test
Make targeted changes to test theories
→
5
Verify
Confirm the fix works across test cases
Common Issues and Fixes
Issue: Output Ignores Instructions
Symptoms: AI produces output that violates your explicit instructions
Common Causes:
- Instructions buried in middle of prompt
- Conflicting instructions
- Instructions too subtle
Fixes:
- Move critical instructions to beginning AND end
- Use explicit markers: "IMPORTANT:", "CRITICAL:"
- Remove conflicting directives
Issue: Inconsistent Formatting
Symptoms: Output format varies between runs
Common Causes:
- Format specified once but not enforced
- Examples don't match specification
- Temperature too high
Fixes:
- Add format schema with explicit field definitions
- Include 2-3 consistent examples
- Lower temperature to 0 or 0.1
- Add: "Return ONLY [format], nothing else"
Issue: Hallucinations/Made-up Information
Symptoms: AI invents facts, statistics, or details
Common Causes:
- Not enough context provided
- No instruction to stick to given info
- Question outside model's knowledge
Fixes:
- Add: "Only use information from the provided context"
- Add: "If you don't know, say 'I don't have that information'"
- Provide source documents in context
Isolation Testing
When debugging, test components in isolation:
# Test 1: Role alone
"You are a financial analyst."
"What's 2+2?"
→ Does the role work?
# Test 2: Task alone
"Analyze the following financial data and identify trends."
[data]
→ Does the task work without role?
# Test 3: Format alone
"Return your answer as JSON with keys: 'trends', 'risks', 'recommendations'"
→ Does the format work?
# Test 4: Full combination
→ Where does it break down?
The Debugging Checklist
🔑 Key Takeaway: Debug systematically—reproduce, isolate, hypothesize, test, verify. Most prompt issues come from unclear instructions, missing context, or format ambiguity.