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Prompt engineer

Skill skillsdirectory/claude-skills/skills/prompt-engineer

Master prompt engineering with classification, summarization, and advanced techniques. Based on Anthropic's Claude Cookbooks and Courses.From its SKILL.md

Install
npx -y skills add skillsdirectory/claude-skills --skill prompt-engineer

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SKILL.md

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Prompt Engineer

You are a master prompt engineer who designs, optimizes, and evaluates prompts for Claude and other LLMs — maximizing accuracy, consistency, and efficiency.

Prompting Techniques

1. Role Prompting

You are a [specific role] with expertise in [domain].
Your task is to [action] for [audience].

2. Few-Shot Prompting

Here are examples of the expected output:

Input: "The product was terrible"
Output: {"sentiment": "negative", "confidence": 0.95}

Input: "I love this app!"
Output: {"sentiment": "positive", "confidence": 0.98}

Now classify this:
Input: "{user_text}"

3. Chain-of-Thought (CoT)

Think through this step by step:
1. First, identify...
2. Then, analyze...
3. Finally, conclude...

Show your reasoning before giving the final answer.

4. XML Tag Structuring

<context>
{background_information}
</context>

<instructions>
{what_to_do}
</instructions>

<output_format>
{expected_format}
</output_format>

Classification Framework

For any classification task:

You are a text classifier. Classify the following text into exactly one category.

Categories:
- URGENT: Requires immediate action
- HIGH: Important but not time-sensitive
- MEDIUM: Standard priority
- LOW: Can be addressed later

Rules:
- Choose ONLY ONE category
- Include confidence score (0-1)
- Briefly explain your reasoning

Text: "{input_text}"

Output as JSON:
{"category": "...", "confidence": 0.XX, "reasoning": "..."}

Summarization Framework

Summarize the following text in [X sentences / X words / X bullet points].

Rules:
- Preserve key facts, numbers, and names
- Maintain the original tone
- Do not add information not in the source
- Start with the most important point

Text:
{long_text}

Prompt Optimization Checklist

  • Specific: Does the prompt clearly define the task?
  • Structured: Is the output format explicitly defined?
  • Constrained: Are there clear boundaries and rules?
  • Examples: Are few-shot examples included?
  • Edge Cases: Are failure modes addressed?
  • Evaluation: Can the output be objectively measured?

Anti-Patterns (Avoid These)

  • ❌ "Do your best" → Be specific about quality criteria
  • ❌ "Be creative" → Define creative boundaries
  • ❌ Long unstructured paragraphs → Use XML tags and bullet points
  • ❌ Ambiguous instructions → Include examples of expected output
  • ❌ No output format → Always specify JSON, markdown, or structured format

Prompt Caching

For repeated prompts with shared context:

  • Place static content (system prompts, examples) at the beginning
  • Place dynamic content (user input) at the end
  • This enables cache hits and reduces costs by up to 90%

What ships with it: 1 file

1.2 KB alongside SKILL.md

Gives 0 of the 12 instructions most prompt engineering skills give in 658 tokens

Counted across 564 of the 626 authors here whose files we hold, read 2026-08-07

  • Ask at most three clarifying questionsin 21 of 564, across 14 files
  • Establish baseline metrics and collect representative examplesin 12 of 564, across 2 files
  • Identify failure modes and prioritize high-impact fixesin 12 of 564, across 2 files
  • Apply prompt and workflow improvements with measurable goalsin 12 of 564, across 2 files
  • Roll back quickly if quality or safety metrics regressin 12 of 564, across 2 files
  • Validate changes with tests and roll out in controlled stagesin 12 of 564, across 2 files
  • Generate quantitative baseline performance reportsin 12 of 564, across 2 files
  • Create representative test scenariosin 12 of 564, across 2 files
  • Treat prompts as codein 12 of 564, across 5 files
  • Preserve the original intentin 12 of 564, across 10 files
  • Test prompts on diverse inputsin 11 of 564, across 7 files
  • Format the output as a markdown templatein 10 of 564, across 4 files

Grouped from the skills themselves: near-identical wordings counted once, and counted by distinct author, so one author publishing three of these counts once. Length counted with cl100k_base; the agent that loads this file may tokenize it differently.

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