Skills jeffallan claude-skills

prompt-engineer

Use it when:
You're writing a prompt or system prompt for an LLM app, or fixing one whose output is inconsistent.
It does:
Defines success criteria and edge cases, picks a prompting pattern, runs test cases, and iterates one change at a time.
You get:
The final prompt in sections, its test cases and results, settings such as temperature and model version, metrics against a baseline, and known limits.
Threshold:
Below 80% accuracy on the test set, it finds the failure patterns before changing the prompt.
Covers:
Few-shot examples, step-by-step reasoning (chain-of-thought), JSON and function-calling schemas, system prompts with guardrails, context limits, and GPT-4, Claude and Gemini differences.

TL;DR

It treats prompts like code: versioned, tested on diverse, realistic inputs including empty and unusual ones, measured with numbers such as accuracy and consistency, and never deployed without that evaluation. It doesn't assume a prompt works the same on another model, and tests across model versions before production. Its examples show a zero-shot sentiment classifier, one given no examples, made more reliable with three labelled ones, and a vague "summarize this" rewritten into exactly three one-sentence bullets. Reference files cover prompt patterns including ReAct, optimization by A/B testing and token reduction, evaluation frameworks, structured outputs, system prompts with persona design and prompt-injection defense, and context management: how quality degrades as a model's context fills.

Summarizes the skill at 078a25c.

npx skills add https://github.com/jeffallan/claude-skills --skill prompt-engineer
Weekly Downloads week to Nov 9, 2026
125
+10% in 8 weeks

Fewer weekly downloads than 76% of skills

Weekly values
Week toInstalls
Sep 21114
Sep 28120
Oct 5109
Oct 12128
Oct 19160
Oct 26140
Nov 2158
Nov 9125
Total Downloads on skills.sh
5,900

Fewer downloads than 76% of skills

Repo stars jeffallan/claude-skills
12,279

More stars than 61% of repos

Age published Jan 20, 2026
9 months

Older than 82% of skills

Category

Build agents, orchestrate workers and give agents memory.

Everything for building software: planning, coding, debugging, design, frameworks, cloud, agents and skills.

Type

A multi-step process the agent follows: interview, debug, run a TDD loop, review.

Effect

Adds no side effects of its own. It shapes how the agent thinks, writes or reviews. Guidelines and routers are always effect:none, even when the task they support edits code.

Needs

Instructions only. Works in any agent that supports skills.

Publisher

Everyone else. Unverified vendor claims default to community.

Topics

SKILL.md

From jeffallan/claude-skills at 078a25c. Checked daily, last changed Nov 6, 2026.

Frontmatter
name: prompt-engineer
description: Writes, refactors, and evaluates prompts for LLMs — generating optimized prompt templates, structured output schemas, evaluation rubrics, and test suites. Use when designing prompts for new LLM applications, refactoring existing prompts for better accuracy or token efficiency, implementing chain-of-thought or few-shot learning, creating system prompts with personas and guardrails, building JSON/function-calling schemas, or developing prompt evaluation frameworks to measure and improve model performance.
license: MIT
metadata:
  author: https://github.com/Jeffallan
  company: https://synergetic.solutions
  version: "1.2.0"
  domain: data-ml
  triggers: prompt engineering, prompt optimization, chain-of-thought, few-shot learning, prompt testing, LLM prompts, prompt evaluation, system prompts, structured outputs, prompt design, context management, lost-in-the-middle, context degradation, token optimization, attention budget
  role: expert
  scope: design
  output-format: document
  related-skills: test-master, rag-architect, debugging-wizard

Prompt Engineer

Expert prompt engineer specializing in designing, optimizing, and evaluating prompts that maximize LLM performance across diverse use cases.

When to Use This Skill

  • Designing prompts for new LLM applications
  • Optimizing existing prompts for better accuracy or efficiency
  • Implementing chain-of-thought or few-shot learning
  • Creating system prompts with personas and guardrails
  • Building structured output schemas (JSON mode, function calling)
  • Developing prompt evaluation and testing frameworks
  • Debugging inconsistent or poor-quality LLM outputs
  • Migrating prompts between different models or providers

Core Workflow

  1. Understand requirements — Define task, success criteria, constraints, and edge cases
  2. Design initial prompt — Choose pattern (zero-shot, few-shot, CoT), write clear instructions
  3. Test and evaluate — Run diverse test cases, measure quality metrics
    • Validation checkpoint: If accuracy < 80% on the test set, identify failure patterns before iterating (e.g., ambiguous instructions, missing examples, edge case gaps)
  4. Iterate and optimize — Make one change at a time; refine based on failures, reduce tokens, improve reliability
  5. Document and deploy — Version prompts, document behavior, monitor production

Reference Guide

Load detailed guidance based on context:

Topic Reference Load When
Prompt Patterns references/prompt-patterns.md Zero-shot, few-shot, chain-of-thought, ReAct
Optimization references/prompt-optimization.md Iterative refinement, A/B testing, token reduction
Evaluation references/evaluation-frameworks.md Metrics, test suites, automated evaluation
Structured Outputs references/structured-outputs.md JSON mode, function calling, schema design
System Prompts references/system-prompts.md Persona design, guardrails, injection defense
Context Management references/context-management.md Attention budget, degradation patterns, context optimization

Prompt Examples

Zero-shot vs. Few-shot

Zero-shot (baseline):

Classify the sentiment of the following review as Positive, Negative, or Neutral.

Review: {{review}}
Sentiment:

Few-shot (improved reliability):

Classify the sentiment of the following review as Positive, Negative, or Neutral.

Review: "The battery life is incredible, lasts all day."
Sentiment: Positive

Review: "Stopped working after two weeks. Very disappointed."
Sentiment: Negative

Review: "It arrived on time and matches the description."
Sentiment: Neutral

Review: {{review}}
Sentiment:
Before/After Optimization

Before (vague, inconsistent outputs):

Summarize this document.

{{document}}

After (structured, token-efficient):

Summarize the document below in exactly 3 bullet points. Each bullet must be one sentence and start with an action verb. Do not include opinions or information not present in the document.

Document:
{{document}}

Summary:

Constraints

MUST DO
  • Test prompts with diverse, realistic inputs including edge cases
  • Measure performance with quantitative metrics (accuracy, consistency)
  • Version prompts and track changes systematically
  • Document expected behavior and known limitations
  • Use few-shot examples that match target distribution
  • Validate structured outputs against schemas
  • Consider token costs and latency in design
  • Test across model versions before production deployment
MUST NOT DO
  • Deploy prompts without systematic evaluation on test cases
  • Use few-shot examples that contradict instructions
  • Ignore model-specific capabilities and limitations
  • Skip edge case testing (empty inputs, unusual formats)
  • Make multiple changes simultaneously when debugging
  • Hardcode sensitive data in prompts or examples
  • Assume prompts transfer perfectly between models
  • Neglect monitoring for prompt degradation in production

Output Templates

When delivering prompt work, provide:

  1. Final prompt with clear sections (role, task, constraints, format)
  2. Test cases and evaluation results
  3. Usage instructions (temperature, max tokens, model version)
  4. Performance metrics and comparison with baselines
  5. Known limitations and edge cases

Coverage Note

Reference files cover major prompting techniques (zero-shot, few-shot, CoT, ReAct, tree-of-thoughts), structured output patterns (JSON mode, function calling), context management (attention budgets, degradation mitigation, optimization), and model-specific guidance for GPT-4, Claude, and Gemini families. Consult the relevant reference before designing for a specific model or pattern.

Maintained by @jeffallan, Principal Consultant at Synergetic Solutions

Documentation