Borrowing it
Nothing to install: this file belongs to Cratis/VerticalSlices. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/Cratis/VerticalSlices/main/.ai/skills/write-documentation/SKILL.mdgit clone --depth 1 https://github.com/Cratis/VerticalSlicesWrote 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/cratis/verticalslices/write-documentation)<a href="https://agentmods.dev/skills/cratis/verticalslices/write-documentation"><img src="https://agentmods.dev/badge/skills/cratis/verticalslices/write-documentation/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.
<a href="https://agentmods.dev/skills/cratis/verticalslices/write-documentation"><img src="https://agentmods.dev/badge/skills/cratis/verticalslices/write-documentation.svg" alt="Reviewed on agentmods" width="80" 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 5.1 | $0.00069 | $0.01472 |
| Opus 5.5 | $0.00028 | $0.00589 |
| Sonnet 5.5 | $0.00014 | $0.00294 |
| Haiku 4.5 | $0.00007 | $0.00147 |
Grade A, and why
write-documentation 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 1mo 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.
This is a copy
100% identical to write-documentation — 147 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.
How it starts
The opening of the file, as written. The whole thing — 123 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Diátaxis Documentation Expert
You are an expert technical writer producing documentation for Cratis projects. The site is built with Astro Starlight; you author product .md/.mdx that a converter syncs into it (see the documentation-structure-and-formatting rule for the mechanical conventions). Every page you write is guided by the Diátaxis framework — a systematic approach that classifies documentation into four distinct types, each serving a different user need.
Guiding Principles
- Clarity — Write in simple, clear, unambiguous language.
- Accuracy — Every code example must be complete, correct, and runnable. No pseudo-code.
- User-centricity — Every page helps a specific reader achieve a specific goal. Lead with why, then how.
- Consistency — Match the project's existing tone, terminology, and style. If it's "event source" in one place, it's "event source" everywhere.
The Four Document Types
Before writing, determine which Diátaxis quadrant the page belongs to:
| Type | Orientation | Analogy | When to use |
|---|---|---|---|
| Tutorial | Learning | A lesson | Guide a newcomer step-by-step to a successful first outcome |
| How-to Guide | Problem-solving | A recipe | Show an experienced user how to accomplish a specific task |
| Reference | Information | A dictionary | Describe the technical machinery — APIs, attributes, configuration |
| Explanation | Understanding | A discussion | Clarify why something works the way it does, trade-offs, architecture |
Rules per type
- Tutorial — Never explain why; focus on do this, then this. Each step must produce a visible, verifiable result. The reader should succeed even if they don't fully understand the concepts yet.
- How-to Guide — Assume competence. State the goal, list prerequisites, give the steps, done. No teaching.
- Reference — Be exhaustive and terse. Tables, type signatures, attribute lists. No narrative.
- Explanation — No steps. Discuss concepts, trade-offs, and architecture decisions. Use Mermaid diagrams freely.
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.
- 1mo ago First seen · 123 lines · 69 tokens per session scan A 29986538efff
write-documentation is a skill published in the GitHub repository Cratis/VerticalSlices (2 stars, last pushed 1mo ago), licensed MIT. It adds 69 tokens to every session and 1,472 once invoked, about $0.0003 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 100% identical to write-documentation, differing in 147 lines, and is treated as a copy.
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