arnesto: Skill for Claude Code

.agents/skills/prd-writer/SKILL.md

prd-writer is a skill for Claude Code from saski/arnesto. It costs 24 tokens per session (484 once invoked), scanned A, a copy of prd-writer, Unlicense.

A tool for writing product requirements documents, or PRDs: structured documents that explain a feature's problem, proposed solution, requirements, and success measures.

In plain words
What is it for?
Use it when starting a feature or product initiative, documenting user needs, defining functional and technical requirements, and preparing work for development.
Why use it?
It turns an early product idea into shared written requirements, reducing confusion about scope and expectations between product, design, and engineering teams.

Skill for Claude Code

Written for Claude Code: argument-hint in frontmatter. Also seen: installed under .agents/ (shared by several agents).

This is saski/arnesto's own configuration. It tells Claude Code how to work on arnesto itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything arnesto configures →

Reuse

Borrowing it

Nothing to install: this file belongs to saski/arnesto. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/saski/arnesto/main/.agents/skills/prd-writer/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/saski/arnesto

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 prd-writer

README.md
[![agentmods](https://agentmods.dev/badge/skills/saski/arnesto/prd-writer.svg)](https://agentmods.dev/skills/saski/arnesto/prd-writer)
Your own site
<a href="https://agentmods.dev/skills/saski/arnesto/prd-writer"><img src="https://agentmods.dev/badge/skills/saski/arnesto/prd-writer.svg" alt="Measured on agentmods" height="20"></a>
Per session 24 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 484 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 100% copy Near-identical to another mod 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 $0.00024 $0.00484
Opus 5 $0.00012 $0.00242
Sonnet 5 $0.00005 $0.00097
Haiku 4.5 $0.00002 $0.00048

Measured 3d ago against content hash 2cf614bc5960, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

prd-writer 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 3d 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.

Origin

This is a copy

100% identical to prd-writer — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.agents/skills/prd-writer/SKILL.md · 76 lines

How it starts

The opening of the file, as written. The whole thing — 76 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Domain Context

This skill implements a proven product management framework. The approach combines best practices from industry leaders and is designed for practical application in day-to-day PM work.

Input Requirements

  • Context about your product, feature, or problem
  • Relevant data, research, or constraints (recommended but optional)
  • Clear articulation of what you're trying to achieve

PRD Writer

When to Use

  • Starting a new feature or product initiative
  • Need to document requirements for the engineering team
  • Stakeholders need a detailed project overview
  • Before beginning design or development work
  • To align cross-functional teams on scope and goals

What This Skill Does

Creates structured, comprehensive PRDs covering problem statement, proposed solution, requirements, success metrics, and implementation details.

Instructions

Help me write a comprehensive PRD for [feature name]. Include:

  1. Problem Statement
  • Current situation
  • User pain points
  • Business impact
  1. Proposed Solution
  • Overview of the approach
  • User stories
  • Success metrics
  1. Requirements
  • Functional requirements
  • Technical requirements
  • Design requirements
  1. Implementation
  • Dependencies
  • Timeline estimate
  • Resources needed
  1. Risks and Mitigations

Your context: [Add product context, feature details, and constraints here]

Best Practices

  • Be specific about the problem and user pain points
  • Include quantitative success metrics
  • Define scope clearly (what's in scope and out of scope)
  • Consider technical constraints upfront
  • Add detailed user stories for key flows
  • Include acceptance criteria

Example

Input: Building a notification center for SaaS app, target users are power users who miss important updates Output: Full PRD with problem statement, user stories, functional/technical requirements, success metrics (reduce missed notifications by 40%), timeline, and risk assessment

Further Reading

Read the full file on GitHub · 76 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. 3d ago First seen · 76 lines · 24 tokens per session scan A 2cf614bc5960

Subscribe to this mod's changes

prd-writer is a skill published in the GitHub repository saski/arnesto (5 stars, last pushed today), licensed Unlicense. It adds 24 tokens to every session and 484 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to prd-writer, differing in 0 lines, and is treated as a copy.

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