prompt-engineer

prompt-engineer is a skill for Claude Code, Codex from sipyourdrink-ltd/bernstein. It costs 15 tokens per session (261 once invoked), scanned A, original, Apache-2.0.

A guide for designing and improving instructions given to large language models, including testing different versions and adapting them to specific models.

In plain words
What is it for?
Use it to write system prompts, choose examples, structure outputs, compare prompt versions, reduce token use, and adapt prompts for Claude, GPT, or Gemini.
Why use it?
It helps make model instructions clearer, more reliable, and less wasteful. It also encourages testing changes against representative examples.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to write system prompts, choose examples, structure outputs, compare prompt versions, reduce token use, and adapt prompts for Claude, GPT, or Gemini.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/sipyourdrink-ltd/bernstein/prompt-engineer
About the project

Bernstein is an open-source governance layer for AI agents that applies written policies, schedules agent work deterministically, controls approvals, and records verifiable execution history. It is used to coordinate CLI coding agents and other agent workloads, including parallel runs and offline review, while the catalogue entries provide its agent workflows and controls.

sipyourdrink-ltd/bernstein · 1,119 stars · on GitHub · bernstein.run

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add sipyourdrink-ltd/bernstein --skill prompt-engineer
Clone the repo
git clone --depth 1 https://github.com/sipyourdrink-ltd/bernstein

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for prompt-engineer

README.md
[![agentmods](https://agentmods.dev/badge/skills/sipyourdrink-ltd/bernstein/prompt-engineer.svg)](https://agentmods.dev/skills/sipyourdrink-ltd/bernstein/prompt-engineer)
Your own site
<a href="https://agentmods.dev/skills/sipyourdrink-ltd/bernstein/prompt-engineer"><img src="https://agentmods.dev/badge/skills/sipyourdrink-ltd/bernstein/prompt-engineer.svg" alt="Measured on agentmods" height="20"></a>
Per session 15 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 261 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 1 finding, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • high System Prompt Leakage · line 20
    Skill contains instructions that could directly expose system prompts, internal rules, or hidden instructions to users or external parties.
    Fix: Remove any instructions that reveal, print, or output system prompts or internal rules. System instructions should never be exposed to end users.
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00015 $0.00261
Opus 5 $0.00008 $0.00130
Sonnet 5 $0.00003 $0.00052
Haiku 4.5 $0.00002 $0.00026

Measured 8d ago against content hash 65386d52abc8, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

prompt-engineer scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 8d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

templates/skills/prompt-engineer/SKILL.md · 38 lines

What it actually says

Prompt Engineering Skill

You are a prompt engineer. Design, test, and optimize LLM prompts and system instructions.

Specialization

  • System prompt design and instruction tuning
  • Few-shot example selection and formatting
  • Chain-of-thought and structured output prompting
  • Prompt evaluation and A/B testing
  • Token budget optimization
  • Model-specific prompt adaptation (Claude, GPT, Gemini)

Work style

  1. Read the task description and existing prompts before writing.
  2. State a clear hypothesis for every prompt change.
  3. Write evaluation cases alongside prompt changes.
  4. Minimize token usage without sacrificing output quality.
  5. Keep prompts in template files, not embedded in application code.

Rules

  • Only modify files listed in your task's owned_files.
  • Test prompts against at least 3 representative inputs before marking complete.
  • Document the intent and expected behavior of each prompt section.
  • Never hardcode model-specific hacks without a comment explaining why.
  • If blocked, post to BULLETIN and move to next task.
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 8d ago First seen · 38 lines · 15 tokens per session scan A 65386d52abc8

Subscribe to this mod's changes

prompt-engineer is a skill published in the GitHub repository sipyourdrink-ltd/bernstein (1,119 stars, last pushed yesterday), licensed Apache-2.0. It adds 15 tokens to every session and 261 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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