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.
npx agentmods add skills/okwinds/miscellany/prd-writing-guidenpx skills add okwinds/miscellany --skill prd-writing-guidegit clone --depth 1 https://github.com/okwinds/miscellanyWrote 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.
[](https://agentmods.dev/skills/okwinds/miscellany/prd-writing-guide)<a href="https://agentmods.dev/skills/okwinds/miscellany/prd-writing-guide"><img src="https://agentmods.dev/badge/skills/okwinds/miscellany/prd-writing-guide.svg" alt="Measured on agentmods" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00155 | $0.04320 |
| Opus 5 | $0.00077 | $0.02160 |
| Sonnet 5 | $0.00031 | $0.00864 |
| Haiku 4.5 | $0.00015 | $0.00432 |
Grade A, and why
prd-writing-guide 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.
How it starts
The opening of the file, as written. The whole thing — 535 lines — stays where its author put it; the contents beside it link to each section on GitHub.
PRD Writing Guide
Overview
Write PRDs so complete that development teams can implement the entire product without asking a single clarifying question.
Skill Workflow Context
This skill is part of a 3-skill pipeline:
┌─────────────────┐ ┌─────────────────┐ ┌─────────────────┐
│ prd-writing- │────►│ prd-to- │ │ reverse- │
│ guide │ │ engineering- │ │ engineering- │
│ │ │ spec │ │ spec │
│ [THIS SKILL] │ │ PRD→Eng Spec │ │ Code→Spec │
└─────────────────┘ └─────────────────┘ └─────────────────┘
For AI Agent products, use `ai-agent-prd` instead (which extends this skill).
Handoff contract: The PRD this skill produces must be complete enough to pass prd-to-engineering-spec's Phase 0 validation without any ❌ items.
The PRD Quality Test
┌─────────────────────────────────────────────────────────────────┐
│ The Developer Test │
├─────────────────────────────────────────────────────────────────┤
│ │
│ Give your PRD to a developer who knows nothing about the │
│ project. Can they: │
│ │
│ □ Understand WHY we're building this? │
│ □ Know exactly WHAT to build (and what NOT to)? │
│ □ Handle EVERY edge case without guessing? │
│ □ Write test cases for EVERY requirement? │
│ □ Estimate the work with confidence? │
│ │
│ If any answer is "no", your PRD is incomplete. │
│ │
└─────────────────────────────────────────────────────────────────┘
Core Principle: Eliminate Ambiguity
What ships with it
12 files 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.
- LICENSE 1.0 KB
- README.md 2.8 KB
- README.zh-CN.md 2.9 KB
- references/ai-features-prd.md 11 KB
- references/common-pitfalls.md 11 KB
- references/completeness-checklist.md 11 KB
- references/discovery-questions.md 12 KB
- references/prd-template.md 13 KB
- references/prioritization-management.md 12 KB
- references/worked-example.md 9.4 KB
- references/writing-style-guide.md 10 KB
- scripts/generate_prd_skeleton.sh 12 KB runs code
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.
- 5d ago First seen · 535 lines · 155 tokens per session scan A c34b873549e5
prd-writing-guide is a skill published in the GitHub repository okwinds/miscellany (50 stars, last pushed 3mo ago), licensed MIT. It adds 155 tokens to every session and 4,320 once invoked, about $0.0008 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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