writing-prompts

writing-prompts is a skill for Claude Code, Codex from ylxmf2005/Longrein. It costs 66 tokens per session (2,766 once invoked), scanned A, original, no licence file.

A guide for writing, rewriting, and reviewing prompts and instructions for coding agents. It examines how each sentence affects what an AI model produces, including files such as AGENTS.md and skill instructions.

In plain words
What is it for?
Use it to improve prompts, agent instructions, skills, sub-agent tasks, and AGENTS.md files.
Why use it?
It helps find wording that sends the model in the wrong direction, adds unwanted implications, or weakens an instruction. The focus is on meaning rather than formatting unless formatting affects understanding.

Skill for Claude CodeCodex

Written for Claude Code and Codex: disable-model-invocation in frontmatter, but also agents/openai.yaml present.

Good fit Use it to improve prompts, agent instructions, skills, sub-agent tasks, and AGENTS.md files.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/ylxmf2005/longrein/writing-prompts
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 ylxmf2005/Longrein --skill writing-prompts
Clone the repo
git clone --depth 1 https://github.com/ylxmf2005/Longrein

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 writing-prompts

README.md
[![agentmods](https://agentmods.dev/badge/skills/ylxmf2005/longrein/writing-prompts/github.svg)](https://agentmods.dev/skills/ylxmf2005/longrein/writing-prompts)
Your own site
<a href="https://agentmods.dev/skills/ylxmf2005/longrein/writing-prompts"><img src="https://agentmods.dev/badge/skills/ylxmf2005/longrein/writing-prompts/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 writing-prompts

Your own site · 80×15
<a href="https://agentmods.dev/skills/ylxmf2005/longrein/writing-prompts"><img src="https://agentmods.dev/badge/skills/ylxmf2005/longrein/writing-prompts.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 66 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,766 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 $0.00066 $0.02766
Opus 5.5 $0.00026 $0.01106
Sonnet 5.5 $0.00013 $0.00553
Haiku 4.5 $0.00007 $0.00277

Measured yesterday against content hash e85940caf2a4, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-30, from the pricing page.

Security

Grade A, and why

writing-prompts 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 yesterday.

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.

skills/writing-prompts/SKILL.md · 88 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

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. yesterday First seen · 88 lines · 66 tokens per session scan A e85940caf2a4

Subscribe to this mod's changes

writing-prompts is a skill published in the GitHub repository ylxmf2005/Longrein (11 stars, last pushed 2d ago), with no licence file. It adds 66 tokens to every session and 2,766 once invoked, about $0.0003 per session on Opus 5.5. 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 2026-09-29.

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