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AI/MLfusengine

prompt-testing

A/B testing and performance metrics for prompts

Stars
13
Source
fusengine/agents
Updated
2026-05-17
Slug
fusengine--agents--prompt-testing
View on GitHubRaw SKILL.md

// install — copy + paste into any project

mkdir -p .claude/skills && curl -fsSL https://raw.githubusercontent.com/fusengine/agents/HEAD/plugins/prompt-engineer/skills/prompt-testing/SKILL.md -o .claude/skills/prompt-testing.md

Drops the SKILL.md into .claude/skills/prompt-testing.md. Works with Claude Code, Cursor, and any agent that loads SKILL.md files from .claude/skills/.

Prompt Testing

Skill for testing, comparing, and measuring prompt performance.

References

  • metrics.md - Load when: defining or scoring Quality/Efficiency/Robustness/UX metrics with thresholds and calculation formulas
  • methodology.md - Load when: running a full A/B test (hypothesis, dataset sizing, statistical significance, common pitfalls)
  • templates.md - Load when: writing a test dataset JSON or an A/B test report

Testing Workflow

1. DEFINE
   └── Test objective
   └── Metrics to measure
   └── Success criteria

2. PREPARE
   └── Variants A and B
   └── Test dataset
   └── Baseline (if existing)

3. EXECUTE
   └── Run on dataset
   └── Collect results
   └── Document observations

4. ANALYZE
   └── Calculate metrics
   └── Compare variants
   └── Identify patterns

5. DECIDE
   └── Recommendation
   └── Statistical confidence
   └── Next iterations

Performance Metrics

Quality

Metric Description Calculation
Accuracy Correct responses Correct / Total
Compliance Format adherence Compliant / Total
Consistency Response stability 1 - Variance
Relevance Meeting the need Average score (1-5)

Efficiency

Metric Description Calculation
Tokens Input Prompt size Token count
Tokens Output Response size Token count
Latency Response time ms
Cost Price per request Tokens × Price

Robustness

Metric Description Calculation
Edge Cases Edge case handling Passed / Total
Jailbreak Resist Bypass resistance Blocked / Attempts
Error Recovery Error recovery Recovered / Errors

For full definitions, thresholds, and the UX metrics category, see metrics.md. For the test dataset and report formats, see templates.md.

Commands

# Create a test
/prompt test create --name "Test v1" --dataset tests.json

# Run an A/B test
/prompt test run --a prompt_a.md --b prompt_b.md --dataset tests.json

# View results
/prompt test results --id test_001

# Compare two tests
/prompt test compare --tests test_001,test_002

Decision Criteria

When to adopt variant B?

IF:
  - Accuracy B >= Accuracy A
  AND (Tokens B <= Tokens A * 1.1 OR accuracy improvement > 5%)
  AND no regression on edge cases
THEN:
  → Adopt B

ELSE IF:
  - Accuracy improvement > 10%
  AND token regression < 20%
THEN:
  → Consider B (acceptable trade-off)

ELSE:
  → Keep A or iterate

Best Practices

  1. Minimum 20 test cases for significance
  2. Include edge cases (15-20% of dataset)
  3. Test multiple runs for consistency
  4. Document hypotheses before testing
  5. Version the prompts being tested