prompt-engineer

prompt-engineer is an agent for Claude Code from matheusallvarenga/claude-code-skills. It costs 40 tokens per session (631 once invoked), scanned A, original, no licence file.

An assistant for improving prompts, the instructions given to language models and other AI systems.

In plain words
What is it for?
Use it to refine prompts, apply prompt-writing patterns, and write system prompts that guide AI behavior.
Why use it?
It helps make AI instructions clearer and more effective when building AI features or trying to improve an agent’s results.

Agent for Claude Code

Written for Claude Code: a Claude Code subagent (agents/*.md). Also seen: model in frontmatter.

Good fit Use it to refine prompts, apply prompt-writing patterns, and write system prompts that guide AI behavior.

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Install with agentmods
npx agentmods add agents/matheusallvarenga/claude-code-skills/prompt-engineer
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.

Clone the repo
git clone --depth 1 https://github.com/matheusallvarenga/claude-code-skills

Made for: Claude Code.

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/agents/matheusallvarenga/claude-code-skills/prompt-engineer/github.svg)](https://agentmods.dev/agents/matheusallvarenga/claude-code-skills/prompt-engineer)
Your own site
<a href="https://agentmods.dev/agents/matheusallvarenga/claude-code-skills/prompt-engineer"><img src="https://agentmods.dev/badge/agents/matheusallvarenga/claude-code-skills/prompt-engineer/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for prompt-engineer

Your own site · 80×15
<a href="https://agentmods.dev/agents/matheusallvarenga/claude-code-skills/prompt-engineer"><img src="https://agentmods.dev/badge/agents/matheusallvarenga/claude-code-skills/prompt-engineer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 40 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 631 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.
Origin unknown 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 $0.00040 $0.00631
Opus 5 $0.00020 $0.00316
Sonnet 5 $0.00008 $0.00126
Haiku 4.5 $0.00004 $0.00063

Measured 8d ago against content hash 6e5d842f3e79, 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.

agents/prompt-engineer.md · 113 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

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 · 113 lines · 40 tokens per session scan A 6e5d842f3e79

Subscribe to this mod's changes

prompt-engineer is an agent published in the GitHub repository matheusallvarenga/claude-code-skills (5 stars, last pushed 5mo ago), with no licence file. It adds 40 tokens to every session and 631 once invoked, about $0.0002 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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