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Get Started Free →Master prompt engineering with classification, summarization, and advanced techniques. Based on Anthropic's Claude Cookbooks and Courses.
.claude/skills/marine-softdrink524-prompt-engineer/SKILL.md| Test case | Without → With | Effect | Δ tokens | Δ turns |
|---|---|---|---|---|
| case-02 | ✗→✓ | ▲ Improved | 43% | 0% |
| case-08 | ✗→✓ | ▲ Improved | 22% | 0% |
| case-13 | ✗→✓ | ▲ Improved | 48% | 0% |
| case-15 | ✓→✗ | ▼ Worse | 28% | 0% |
| case-10 | ✓→✓ | = Same ✓ | 69% | 0% |
You are a master prompt engineer who designs, optimizes, and evaluates prompts for Claude and other LLMs — maximizing accuracy, consistency, and efficiency.
You are a [specific role] with expertise in [domain].
Your task is to [action] for [audience].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}"Think through this step by step:
1. First, identify...
2. Then, analyze...
3. Finally, conclude...
Show your reasoning before giving the final answer.<context>
{background_information}
</context>
<instructions>
{what_to_do}
</instructions>
<output_format>
{expected_format}
</output_format>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": "..."}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}For repeated prompts with shared context:
| Case | Status | Duration (ms) | Turns | Tokens | Tool calls | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Without | With | Δ | Without | With | Δ | Without | With | Δ | Without | With | Δ | ||
case-10 | pass→pass | 7,891 | 8,895 | +13% | 1 | 1 | 0% | 1,413 | 2,389 | +69% | 0 | 0 | — |
case-01 | fail→fail | 11,052 | 9,785 | -11% | 1 | 1 | 0% | 2,002 | 2,486 | +24% | 0 | 0 | — |
case-02 | fail→pass | 9,268 | 8,945 | -3% | 1 | 1 | 0% | 1,655 | 2,360 | +43% | 0 | 0 | — |
case-03 | pass→pass | 8,510 | 8,071 | -5% | 1 | 1 | 0% | 1,914 | 2,568 | +34% | 0 | 0 | — |
case-04 | pass→pass | 13,737 | 9,819 | -29% | 1 | 1 | 0% | 2,630 | 2,534 | -4% | 0 | 0 | — |
case-05 | pass→pass | 5,273 | 6,736 | +28% | 1 | 1 | 0% | 1,135 | 2,163 | +91% | 0 | 0 | — |
case-06 | pass→pass | 14,672 | 10,264 | -30% | 1 | 1 | 0% | 2,621 | 2,676 | +2% | 0 | 0 | — |
case-07 | fail→fail | 12,986 | 11,632 | -10% | 1 | 1 | 0% | 2,149 | 2,712 | +26% | 0 | 0 | — |
case-08 | fail→pass | 13,025 | 11,631 | -11% | 1 | 1 | 0% | 2,396 | 2,922 | +22% | 0 | 0 | — |
case-09 | pass→pass | 8,191 | 9,339 | +14% | 1 | 1 | 0% | 1,440 | 2,375 | +65% | 0 | 0 | — |
case-11 | fail→fail | 12,972 | 7,671 | -41% | 1 | 1 | 0% | 2,154 | 2,053 | -5% | 0 | 0 | — |
case-12 | pass→pass | 7,480 | 6,633 | -11% | 1 | 1 | 0% | 1,286 | 1,796 | +40% | 0 | 0 | — |
case-13 | fail→pass | 8,335 | 8,397 | +1% | 1 | 1 | 0% | 1,484 | 2,195 | +48% | 0 | 0 | — |
case-14 | pass→pass | 12,306 | 10,915 | -11% | 1 | 1 | 0% | 2,573 | 3,107 | +21% | 0 | 0 | — |
case-15 | pass→fail | 11,671 | 11,776 | +1% | 1 | 1 | 0% | 2,180 | 2,791 | +28% | 0 | 0 | — |
case-16 | pass→pass | 11,974 | 12,108 | +1% | 1 | 1 | 0% | 2,117 | 2,923 | +38% | 0 | 0 | — |
case-17 | pass→pass | 11,835 | 10,614 | -10% | 1 | 1 | 0% | 2,119 | 2,601 | +23% | 0 | 0 | — |
case-18 | pass→pass | 9,450 | 6,618 | -30% | 1 | 1 | 0% | 1,999 | 1,996 | -0% | 0 | 0 | — |
case-19 | pass→pass | 9,209 | 6,294 | -32% | 1 | 1 | 0% | 1,636 | 1,804 | +10% | 0 | 0 | — |
case-20 | pass→pass | 8,048 | 5,946 | -26% | 1 | 1 | 0% | 1,462 | 1,764 | +21% | 0 | 0 | — |
case-21 | pass→pass | 13,037 | 13,627 | +5% | 1 | 1 | 0% | 2,320 | 3,203 | +38% | 0 | 0 | — |
case-22 | pass→pass | 12,169 | 8,549 | -30% | 1 | 1 | 0% | 2,328 | 2,351 | +1% | 0 | 0 | — |
DecimalAI ran this skill against gemini-3.6-flash twice over the same eval suite — once with the skill loaded and once without — and compared the two runs case by case. 22 cases were attempted. The headline lift of +9 percentage points is the difference between those two pass rates over the 22 comparable cases. 1 case got worse with the skill loaded, and it is included in that figure.
Without the skill loaded, the model failed this case. With it loaded, the same prompt on the same model passed. This is one improved case from the latest verified run; every case, including any that regressed, is in the table above.
Other measured skills in the registry, with their headline benchmark lift.