prompt-engineering

prompt-engineering is a skill for Claude Code from PhAlves23/prompt-engineering-skill. It costs 132 tokens per session (2,819 once invoked), scanned A, original, MIT.

A prompt-rewriting skill that improves instructions written for AI models and returns a revised prompt with a short change log.

In plain words
What is it for?
Use it to refine prompts for models such as Claude, OpenAI models, or Gemini when the desired result, audience, or output format needs to be clearer.
Why use it?
It helps remove unclear wording and missing structure before a prompt is used, without carrying out the prompt's task.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: mentions subagents.

Part of the prompt-engineering plugin — 1 skill shipped together

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.

agentmods
npx agentmods add skills/phalves23/prompt-engineering-skill/prompt-engineering
Any agent
npx skills add PhAlves23/prompt-engineering-skill --skill prompt-engineering
Clone the repo
git clone --depth 1 https://github.com/PhAlves23/prompt-engineering-skill

Made for: Claude Code.

Or install prompt-engineering, the plugin that ships this one along with the rest of its 1 skill.

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-engineering

README.md
[![agentmods](https://agentmods.dev/badge/skills/phalves23/prompt-engineering-skill/prompt-engineering.svg)](https://agentmods.dev/skills/phalves23/prompt-engineering-skill/prompt-engineering)
Your own site
<a href="https://agentmods.dev/skills/phalves23/prompt-engineering-skill/prompt-engineering"><img src="https://agentmods.dev/badge/skills/phalves23/prompt-engineering-skill/prompt-engineering.svg" alt="Measured on agentmods" height="20"></a>
Per session 132 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,819 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00132 $0.02819
Opus 5 $0.00066 $0.01409
Sonnet 5 $0.00026 $0.00564
Haiku 4.5 $0.00013 $0.00282

Measured 5d ago against content hash 3e0ee50ac431, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

prompt-engineering 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 5d 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.

plugins/prompt-engineering/skills/prompt-engineering/SKILL.md · 128 lines

How it starts

The opening of the file, as written. The whole thing — 128 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Prompt Engineering

Turns a raw draft into a production-grade prompt by applying proven prompt engineering techniques. Distilled from primary sources (Anthropic prompting best practices + prompt improver, OpenAI GPT-5/reasoning guides, Google Gemini PTCF, The Prompt Report) — see references/ for the full material.

Purpose

The user sends a prompt draft (or describes what they want). The skill returns a rewritten, optimized version, ready to paste, plus a short changelog of what changed and why. It is not meant to answer the prompt — it is meant to improve the prompt.

Operating principle

  • Improve the prompt, don't run it. This skill rewrites the prompt; it does not respond to the task the prompt describes. If the request is ambiguous (the user pasted a prompt without saying what they want), the default is to optimize the prompt and, at the end, offer to run it. Only execute the task if the user explicitly asks ("run this prompt", "answer this").
  • Produce directly. Don't ask for permission. Only ask clarifying questions (1–3, max) when missing information would materially change the rewrite — expected output type, target model, or audience. If unanswered, assume the most sensible default, state the assumption in the changelog, and proceed.
  • Calibrate effort to complexity. Simple prompt (lookup, formatting) → lean structural rewrite, no inflating with CoT/examples. Complex prompt (reasoning, classification, generation with criteria, agentic) → full structure. Don't decorate beyond what's needed — prompt over-engineering hurts latency and cost with no gain.
  • If the draft is already good, say so and do the minimum. Don't invent changes to justify the rewrite. Apply the anti-overengineering rule to yourself: when the prompt already has solid role, structure, scope, and output contract, deliver only the marginal tweaks that genuinely add value and state that the rest was already good. Rewriting a good prompt into something "different but not better" is a failure.
  • Optimize for the right model. The default is Claude 4.x. If the user indicates another target (GPT/o-series, Gemini), adjust per references/model-profiles.md — the rules diverge (e.g. reasoning models do NOT want "think step by step").

Read the full file on GitHub · 128 lines

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. 5d ago First seen · 128 lines · 132 tokens per session scan A 3e0ee50ac431

Subscribe to this mod's changes

prompt-engineering is a skill published in the GitHub repository PhAlves23/prompt-engineering-skill (9 stars, last pushed 3mo ago), licensed MIT. It adds 132 tokens to every session and 2,819 once invoked, about $0.0007 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 2026-08-31.

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