# Agent Skill to Force Docs in ASD-STE100 Simplified Technical English > Source: > Published: 2026-07-30 19:34:27+00:00 An agent skill that forces LLMs to write docs in [ASD-STE100 Simplified Technical English](https://www.asd-ste100.org/): the controlled language aerospace has used since 1983 so a tired mechanic *cannot* misread an instruction. AI slop dies as a side effect. 💀 [See it](#-before--after) · [Install](#-install) · [The rules](#-the-rules) · [Not just docs](#-not-just-docs) · [Receipts](#-receipts) · [FAQ](#-faq) Works in every harness that speaks the [Agent Skills standard](https://agentskills.io): Claude Code, Cursor, VS Code Copilot, OpenAI Codex, Gemini CLI, Goose, OpenCode, and ~25 more. One folder, no dependencies, MIT. Left column is **real unedited Claude output**. Right column is the same model with the skill loaded. | 🤖 Without skill | | |---|---| | | | | | | ``` ┌── measured: 6 Claude models × 8 tasks × 2 conditions, 96 runs ──┐ │ STE violations per 100 words ▼ 72.9% (every model won) │ │ output tokens ▼ on all 6 models │ │ mean sentence length 11.2 → 9.7 words │ │ "seamlessly" survived 0 │ └─────────────────────────────────────────────────────────────────┘ ``` More rewrites in [ examples/before-after.md](/AminBlg/SimpleEnglish/blob/main/examples/before-after.md): READMEs, error messages, incident reports, release notes. ``` npx skills add AminBlg/SimpleEnglish ``` That is it. The [skills CLI](https://github.com/vercel-labs/skills) detects your agents (Claude Code, Cursor, Codex, Copilot, Gemini CLI, and more) and installs for the ones you pick. Try before installing: ``` npx skills use AminBlg/SimpleEnglish@simple-english ``` No SKILL.md support at all? Paste [ prompts/system-prompt.md](/AminBlg/SimpleEnglish/blob/main/prompts/system-prompt.md) into your system prompt, AGENTS.md, or `.cursorrules` . There is even a ~60-token version for tight budgets.Then ask for any technical writing, or say: *"rewrite this with simple-english"*. **Claude.ai** (paid plans) supports skills natively: - Download the skill file: open [SKILL.md](https://github.com/AminBlg/SimpleEnglish/raw/main/skills/simple-english/SKILL.md)and save it (Ctrl+S / Cmd+S). - In claude.ai, go to **Settings → Capabilities** and turn on code execution. - Go to **Settings → Customize → Skills → Upload** and upload the saved`SKILL.md` . - Toggle the skill on. Done. Claude applies it when you ask for technical writing. **ChatGPT**: no skill support, so use the prompt version. Copy the block from [ prompts/system-prompt.md](/AminBlg/SimpleEnglish/blob/main/prompts/system-prompt.md) into **Settings → Personalization → Custom Instructions**, or into the instructions of a Project or Custom GPT. **Gemini**: create a Gem and paste the same block into its instructions. **Any other chatbot**: attach or paste `prompts/system-prompt.md` into the chat and say "apply this to everything you write for me". 53 numbered rules, 9 sections, written in 1983 by people whose readers die when a sentence is ambiguous. The ones doing the heavy lifting: | Rule | What it kills 🪦 | |---|---| | Max 20 words per instruction, 25 per description | The run-on sentence | | One word = one meaning, whole document | check/verify/confirm/validate roulette | | Simple tenses only | "has been updated" → "we updated" | | No "-ing" verb forms | ", making it easy to..." clauses | | Active voice | "it should be noted that" | | No should/would/may/might | Hedging. (`can` , `will` , `must` survive) | | Condition BEFORE command | Trailing "...if the flag is set" that readers execute too late | | One instruction per sentence | Steps nobody can follow at 2 a.m. | | Keep articles, keep "that" | Telegraph style. STE is short, not terse | Full paraphrased set with software examples: [ SKILL.md](/AminBlg/SimpleEnglish/blob/main/skills/simple-english/SKILL.md). Yes, this README breaks half of them. Marketing is explicitly out of STE scope. The skill knows that and stays in the docs. 😌 The skill ships adaptations ([ use-cases.md](/AminBlg/SimpleEnglish/blob/main/skills/simple-english/references/use-cases.md)) for: - 🚨 **Error messages**: what happened → why → what to do, in that order - 📟 **Runbooks**: STE's home turf; a runbook IS a maintenance manual - 🧯 **Incident reports**: simple past murders "we have identified an issue that may have impacted" - 📣 **Release notes**: breaking changes as warnings: command first, risk second - 🤖 **Your AGENTS.md / prompts**: a system prompt is a procedure for a reader that cannot ask questions. Models read "should" as optional. STE bans "should". Think about it. - 🌍 **Translation prep**: STE's original job: readable for non-natives, cheap to localize Where it refuses to go: marketing copy, blog voice, brand writing. Flat on purpose. ✋ **72.9% fewer STE violations per 100 words with the skill on, averaged across 6 models × 8 writing tasks (96 generations, measured).** | Model | Baseline viol/100w | Skill viol/100w | Reduction | |---|---|---|---| | claude-opus-4-8 | 1.05 | 0.62 | 41% | | claude-opus-4-7 | 2.28 | 0.42 | 82% | | claude-opus-4-6 | 2.24 | 0.40 | 82% | | claude-opus-4-5 | 2.55 | 0.57 | 78% | | claude-sonnet-5 | 2.67 | 0.53 | 80% | | claude-sonnet-4-6 | 2.06 | 0.52 | 75% | Output tokens went DOWN on all six models too (the skill writes shorter). Deterministic regex linter, same rules for both conditions, honest-caveat list and full method in [ evals/results/RESULTS.md](/AminBlg/SimpleEnglish/blob/main/evals/results/RESULTS.md). Reproduce with `python3 evals/run_bench.py` — needs only a logged-in Claude Code CLI.Built TDD-style against the **primary Issue 9 text** (2025), not blog summaries: - Baseline agents without the skill wrote 40-word sentences and **invented rule numbers**. One confidently cited "Rule 3.1: short sentences" (real Rule 3.1 is verb forms 💀) - Secondary sources online are wrong about the modals: `can` and`will` ARE approved. We checked the PDF. - The skill was written to close each recorded baseline failure, then re-tested until agents pass. Scenarios + recorded results: `evals/pressure-tests.md` **Does this make output STE-certified?** No. Nothing does, because ASD certifies no tool. Default mode is pragmatic: structural rules + your domain vocabulary. Strict mode gets close; word-level rulings live in the official standard, a [free download](https://www.asd-ste100.org/request.html). **Will my docs sound robotic?** They will sound like Airbus manuals: flat and impossible to misread. For docs that is the whole point. Keep your voice for your blog. ✍️ **Why not just prompt "write clearly"?** "Clearly" is an opinion. "No sentence over 20 words" is a spec. Agents follow specs. 📐 **Why a 40-year-old aerospace standard?** Because it is not vibes. It is maintained (Issue 9, January 2025), numbered, and testable. And it happens to be a near-perfect negative of every AI writing tell. MIT for everything here. The repo paraphrases the rules for teaching and reproduces **zero** spec text or dictionary content. Unofficial project, not affiliated with or endorsed by ASD or STEMG. ASD-STE100 is a registered trademark of ASD.