/asd-ste100-skill

name: asd-ste100
description: "Use when English text must be parsed without a human to resolve ambiguity — tool descriptions, error messages, inter-agent instructions, system prompts, status reports — and misreading has a real cost, or when text reads as dense, hedged, or easy to misparse. Triggers: disambiguate, STE100 rewrite, apply Simplified Technical English, plain-language rewrite, controlled-language rewrite, rewrite so an agent cannot misread this. Not for creative or marketing copy."
version: 0.4.0

Simplified Technical English (ASD-STE100)

ASD-STE100 is a controlled-language standard built by the aerospace and defense industry (ASD, the AeroSpace and Defense Industries Association of Europe) to stop maintenance technicians from misreading English instructions. The standard removes the two biggest sources of misreading: words with more than one meaning, and sentences with more than one possible structure.

This skill borrows that same discipline for a different reader: an **AI agent or a downstream system** that has to parse an English string — an error message, a tool description, an inter-agent instruction, a status report — without a human in the loop to resolve ambiguity. If a maintenance technician can misread "close the valve" as an adjective ("the valve that is near") instead of a command, so can a language model.

When to Use This Skill

• An agent's output (explanation, instruction, log message, tool description) reads as dense, jargon-heavy, or ambiguous.
• Text will be consumed by another agent, a translation pipeline, or a non-native English reader, and misparsing has a real cost.
• You are writing a prompt, system message, or tool description and want to remove ambiguity before a model ever sees it.
• You want a **before/after** comparison showing exactly which rule was violated and how the rewrite fixes it. Ask for it — the default output is the rewritten text alone (see Output Format).

This skill is not for creative or marketing copy — STE is deliberately flat and literal. Do not apply it to text where voice, nuance, or persuasion is the point.

Two Modes

Pick a mode before rewriting. If the user does not say which, infer it from the text type. Keep the choice internal unless the user asks for the rule table (see Output Format).

**Strict** — procedures, error messages, tool and function descriptions, inter-agent instructions, safety text. Anywhere a wrong reading has a cost. Apply every rule below, including the hard length caps and one-word-one-meaning discipline.

**STE-flavored** — READMEs, PR descriptions, changelogs, explanatory prose. Apply the structural rules in full and treat the lexical rules as advisory (see Core Rewrite Rules for that split). In practice that means keeping the sentence length caps, active voice, simple tenses, no phrasal verbs, no semicolons, no nominalization and no marketing adjectives, while dropping the one-word-one-meaning lockdown: prose needs some range, and a strict rewrite of prose reads as a personality transplant rather than a clarification.

The two modes and the structural/lexical split are the same distinction seen from two directions. The split says which rules this skill can verify without ASD's dictionary. The modes say which of them to enforce for a given kind of text.

Source and Scope

This skill encodes the **rule categories** of ASD-STE100 Issue 9 (Jan 2025): 53 writing rules across 9 sections covering word choice, grammar, sentence structure, and style, backed by a dictionary of ~900 approved words (one meaning, one part of speech each) and ~1,200 words to avoid with suggested replacements. See `references/writing-rules.md` for the full rule summary and citations.

It does **not** reproduce ASD's ~900-word approved dictionary verbatim. ASD-STE100 is free to obtain, but it is not free to redistribute: Issue 9, page 2 states that "no reproduction or publication of it, in whole or in part, shall be made without the written authority of an officer of ASD," and grants free reproduction rights only to eight listed categories (ASD/AIA/AIAC member associations and their member companies and customers, member-state defence ministries, A4A, airworthiness authorities, and universities and research institutes for educational purposes). This project is in none of them, so the dictionary stays out of this repo.

Instead, this skill applies the *underlying principle* (pick the plainest, most common word available and use it the same way every time) rather than checking against a fixed word list. When exact ASD-approved wording matters (e.g. actual aircraft maintenance documentation), get the standard and check word-by-word against the real dictionary. Request it from the [official downloads page](https://www.asd-ste100.org/STE_downloads.html) — note that this is a request form that emails you a link, not a direct download.

Core Rewrite Rules

STE's rules divide into two kinds, and this skill can only fully deliver one of them. **Structural rules** are self-contained: they describe sentence shape, and you can apply them from the description alone. **Lexical rules** are defined entirely by the official ~900-word dictionary, which this skill deliberately does not reproduce (see Source and Scope). Without that dictionary, the lexical rules degrade from a checkable standard into a preference for plain words.

Apply the structural rules with confidence. Apply the lexical rules as a direction of travel, and say so in your output rather than implying dictionary compliance you cannot verify.

Structural rules — apply these

| Rule | Do | Don't | |---|---|---| | Active voice | "The agent deletes the file." | "The file is deleted (by the agent)." — unless the actor is genuinely unknown or irrelevant | | No phrasal verbs (Rule 9.3) | "Remove the panel." / "Start the job." | "Take off the panel." / "Spin up the job." — a two-word verb has meanings the parts do not predict | | One instruction per sentence | "Op