Prompt Engineering Advanced: System Prompts, Persona, Evaluation

Three scenarios, 6 real Skills, build production-grade prompts

Deep Skill Finder

Sound familiar?

Anthropic's interactive Prompt Engineering tutorial went viral and exposed how most of us still write prompts at the add-one-magic-sentence level, never thinking from how models actually work.
source: X · prompt engineering
Same AI, wildly different results. My vague prompts get vague outputs, and after a dozen revision rounds everything is still unstable — I cannot even tell which sentence is the problem.
source: Reddit · r/PromptEngineering
My system prompt is a wall of text, yet the model still goes out of bounds and ignores formats. How do you design constraints that actually cannot be bypassed?
source: GitHub · LLM app dev

Real voices scattered across Reddit / Hacker News / X / dev forums — stitched together, this is what people go through when doing "Prompt Engineering Advanced".

Lazy path · recommended
Install deep-skill-finder once — let your Agent find Skills for you
Whatever "Prompt Engineering Advanced" task you have, MEYO already has the matching Skills. You don't need to hunt one by one — install deep-skill-finder and your Agent will auto-search MEYO's 50,000+ Skill library on every task, recommending the best match. You just say what you want to do — matching Skills is the Agent's job.
Copy → paste into Claude Code / Codex / Cursor / WorkBuddy / CatPaw · Agent installs automatically:
Please install the deep-skill-finder skill: download the archive from https://www.meyo.life/skill-finder, extract it into your local skill directory and enable it.

Or browse common-scene Skills below. Learn more about deep-skill-finder → meyo.life/skill

Three scenarios, 2 real Skills each

Install them all, or just pick 1–2 by name. Don't worry about picking wrong — they're free, uninstall anytime.

System Prompt Design

From layered architecture to injection defense — write system prompts that are powerful and hard to bypass

For AI product builders

System prompt architecture design
Focused on LLM prompt design and optimization: system prompt architecture, chain-of-thought design and few-shot strategies
515 users
Boundaries and injection defense
For AI product builders: design robust system prompt boundaries and recognize injection and leakage risks
61 users

Persona Engineering

Design an agent's identity, tone, boundaries and behavior spec instead of three throwaway sentences

For agent product teams

Agent personality with a SOUL.md template
Create a distinctive agent personality with a detailed SOUL.md template covering identity, traits, expertise, response style and safety rules
1617+ users
A persona-building workflow
A complete workflow — tone, name, personality, background, relationships and speech rhythm — for building lifelike personas
760 users

Debug and Evaluate

Replace change-a-line-and-pray with test cases and automated scoring for evidence-based iteration

For teams that need stability

prompt-eval TOP 1
A 6-step prompt evaluation flow
Evaluate and refine any prompt: test plan, roughly 50 test cases, prompt execution, an evaluator prompt and automated scoring
992 users
Diagnose unexpected outputs
Debug prompts that misfire: diagnose failure modes, spot ambiguous and conflicting instructions, test variants and compare responses
518 users

💬 Join the Deep Skill Finder Community

Trade "Prompt Engineering Advanced" workflows with other Deep Skill Finder users and get install help

QR code to join the Deep Skill Finder Discord community

FAQ

Q: What is prompt engineering actually about?
A: Three things: translating your needs into instructions the model understands precisely (clarity), giving the model the right reasoning path (chain-of-thought, few-shot), and locking output with formats and constraints (structure). The three scenarios on this page map to these three layers.
Q: Are longer prompts better?
A: No. A long, vague prompt performs worse than a short, precise one. Good prompts have a clear structure of role, task, context, format and constraints — extra description dilutes the key instructions. Optimization skills can help you cut the fat.
Q: How do I get the model to output reliable JSON?
A: Two layers: first, specify the schema and examples clearly in the prompt; second, enforce schema-constrained decoding via the API's response_format or tool_use. Prompt-only constraints occasionally fail to parse under strict requirements. The Structured Output scenario on this page covers both layers.
Q: What is the difference between a system prompt and a user prompt?
A: The system prompt defines the model's role, capabilities and boundaries, takes priority over user input, and acts as your product's constitution. The user prompt is the specific instruction for each turn. Because system prompts must resist injection and privilege escalation, they need dedicated boundary design. See the System Prompt Design scenario on this page.
Q: I have hit a wall tweaking my prompt. What now?
A: Stop guessing. Write the expected behavior as test cases, use evaluation skills to score automatically, and iterate on one dimension at a time (clarity, format, constraints). Data-driven iteration converges far faster.
Q: How do I install these Skills?
A: Click the Copy button on each skill card and paste the full install command into your agent (such as Claude Code). Once installed, your agent will invoke the right skill automatically in matching scenarios.

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