Replaces trial-and-error prompt engineering with structured methodology: objective definition, current prompt analysis, variant generation (instruction clarity, example strategies, output format specification), evaluation rubric design, test case creation, and failure mode identification.
| references/prompt-patterns.md | Prompt structure catalog: zero-shot, few-shot, CoT, persona, structured output | Always | | references/evaluation-metrics.md | Quality metrics (accuracy, format compliance, completeness), rubric design | Evaluation needed |
| references/failure-modes.md | Common prompt failure taxonomy, detection strategies, mitigations | Failure analysis requested | | references/output-constraints.md | Techniques for constraining LLM output format, JSON mode, schema enforcement | Format control needed |
Systematic LLM prompt engineering: analyzes existing prompts for failure modes, generates structured variants (direct, few-shot, chain-of-thought), designs evaluation rubrics with weighted criteria, and produces test case suites for comparing prompt performance. Triggers on: "prompt engineering", "prompt lab", "generate prompt variants", "A/B test prompts", "evaluate prompt", "optimize prompt", "write a better prompt", "prompt design", "prompt iteration", "few-shot examples", "chain-of-thought prompt", "prompt failure modes", "improve this prompt". Use this skill when designing, improving, or evaluating LLM prompts specifically. NOT for evaluating Claude Code skills or SKILL.md files — use skill-evaluator instead. Source: mathews-tom/praxis-skills.