Merge pull request #758 from mattpocock/docs-wfa-rewrite

docs: rewrite the writing-for-agents page around what people get wrong

docs/productivity/writing-for-agents.md

@@ -1,30 +1,70 @@
 ## What it does
 
-`writing-for-agents` is the reference you write agent-facing documents against — skills, `AGENTS.md` / `CLAUDE.md`, and any doc an agent reaches by a pointer. The packaging differs; the writing does not: the same levers make each one predictable, so the agent takes the same *process* every run rather than producing the same output.
+`writing-for-agents` is the reference you write agent-facing documents against — a skill, an `AGENTS.md` / `CLAUDE.md`, a spec, a runtime prompt, a README, any doc an agent reads. The packaging differs; the writing does not: the same levers make each one predictable, so the agent takes the same *process* every run rather than producing the same output.
 
-Formerly `writing-great-skills`. The rename tracks what the reference always was underneath: almost none of it is skill-specific. The universal core — context pointers, the two loads, the information hierarchy, completion criteria, leading words, pruning — applies to any document an agent consumes; the genuinely skill-only mechanics (frontmatter, the model- vs user-invoked choice, router skills) are disclosed to a linked `SKILL-MECHANICS.md` you read only when the document you're writing is a skill.
+Its default move is deletion, not explanation. Ask an agent to write instructions for another agent and it spends most of its words explaining what the model already knows — every one of those lines is a **no-op**, paying context and changing no behaviour. This reference is the lens that finds them, which is why it earns its keep at least as often on a document you already have as on a blank file.
+
+It was called `writing-great-skills` until v1.1. The rename tracks what it always was underneath: almost none of it is skill-specific. The skill-only mechanics — frontmatter, the model- versus user-invoked choice, router skills — are disclosed to a linked `SKILL-MECHANICS.md` you read only when the document in front of you is a skill.
 
 ## When to reach for it
 
-The agent reaches for it on its own whenever you're creating or editing a skill, or modifying `AGENTS.md` or `CLAUDE.md` — and you can still type `/writing-for-agents` to pull it up directly.
+Type `/writing-for-agents`, or the agent reaches for it on its own when you're creating or editing a skill, or modifying `AGENTS.md` or `CLAUDE.md`.
+
+Reach for it by hand for everything else an agent reads: your docs, specs and tickets, system and AFK prompts. The test is one question — does an agent read this? — and it does not matter how the document gets in front of it, whether a pointer names it, a human pastes it, or it simply sits in the repo. For working out what a codebase actually contains in the first place, use [grill-with-docs](https://aihero.dev/skills-grill-with-docs) — this reference governs how a document reads, not what it knows.
 
 ## The two loads
 
-The concept the whole reference turns on is a pair of budgets every document and pointer spends:
+The idea the whole reference turns on is a pair of budgets every document and pointer spends:
 
 - **Context load** — the cost of always-loaded material on the agent's window: an `AGENTS.md` line, a skill description, anything sitting in context every turn whether or not it fires.
-- **Cognitive load** — the cost on the human: which documents exist and when to reach for each. You are the index. Not a cost to minimise — it's the price of human agency.
+- **Cognitive load** — the cost on you: which documents exist, and when to reach for each. You are the index. Not a cost to minimise — it is the price of human agency.
 
-Once you're thinking in these two loads, most authoring decisions — split or don't, inline or disclose, point or push — become the same trade made in different places.
+Once you think in these two loads, most authoring decisions — split or don't, inline or disclose, point or push — become the same trade made in different places.
 
-## The other levers
+## The levers
 
-- **Context pointers** — the reference held in context that names out-of-context material and encodes when to reach it. A skill description and an `AGENTS.md` line pointing at a doc are the same object; the pointer's *wording*, not its target, decides when and how reliably the agent reaches through it.
-- **Information hierarchy** — the ladder from in-file step, to in-file reference, to disclosed reference behind a pointer. **Progressive disclosure** is the move down that ladder so the top stays legible; **co-location** decides what sits beside each piece once placed.
-- **Completion criteria** — the clarity and demand of each step's done-condition, and the **legwork** it drives; the defence against **premature completion**.
-- **Leading words** — a compact concept already in the model's pretraining (*tight*, *red*, *tracer bullet*) that the agent thinks with while running the document; hunt restatements a single word can retire.
-- **Pruning** — single source of truth, relevance, and the no-op test applied sentence by sentence, against **sediment** and **sprawl**. Single source of truth reaches past the document into the environment: a doc restating what's already in `package.json`, a config file, or `--help` output is a **cache** of a lookup that was never expensive, and it's the copy that goes stale. Cache what the agent can't find by looking — the unwritten convention, the reason behind a choice.
+- **Context pointers** — the reference held in context that names out-of-context material and encodes when to reach it. A skill description and an `AGENTS.md` line naming a doc are the same object; the pointer's *wording*, not its target, decides how reliably the agent reaches through it.
+- **Information hierarchy** — the ladder from in-file step, to in-file reference, to disclosed reference behind a pointer. **Progressive disclosure** is the move down that ladder so the top stays legible.
+- **Completion criteria** — the clarity and demand of each step's done-condition, and the **legwork** that demand drives; the defence against **premature completion**.
+- **Leading words** — a compact concept already in the model's pretraining (*tight*, *red*, *tracer bullet*) that the agent thinks with while running the document. It anchors twice: execution in the body, invocation in the pointer.
+- **Pruning** — single source of truth, relevance, and the no-op test applied sentence by sentence, against **duplication**, **sediment** and **sprawl**.
+
+## Common questions
+
+**Where did `/writing-great-skills` go?**
+It is this skill, renamed in v1.1. Practitioners were already pointing it at `AGENTS.md`, docs, specs, tickets and runtime prompts long before the name caught up; structure, leading words and pruning turn out to be the craft of any text an agent reads. There is no alias — reinstall under the new name.
+
+**"Writing for agents" — so the agent does the writing?**
+The other way round. You are the author; the agent is the reader. That is the whole difficulty of the genre: you are writing for a reader who has already read everything, so explanation is waste and precision is the entire job.
+
+**Can't I just ask the agent to write it for me?**
+You can, and it will produce something verbose. Left alone the model explains what it already knows, and it will not apply the no-op test or reach for a leading word on its own. Use the reference on the draft — a review pass is where most of its value lands.
+
+**I asked an agent to trim a document and it cut the functionality.**
+Agents told to "streamline" optimise for length, because length is the thing they can see. The no-op test is behavioural, not aesthetic: delete the line and ask whether the agent's behaviour changed. When a sentence fails, delete the whole sentence rather than trim words from it — and settle a disagreement about it by running the document, not by arguing.
+
+**How do I know when it's done?**
+When it works, and you can no longer find duplication, sediment or no-ops. There is no automated eval here; the check is a manual run plus the failure-mode vocabulary as a diagnostic. When a document misbehaves, that vocabulary is also the repair kit — name the failure mode first, then fix that.
+
+**Should this live in `CLAUDE.md` or somewhere else?**
+Ask which load you want to pay. `CLAUDE.md` loads into every session unconditionally; material behind a pointer costs only the pointer's own line until it fires. Anything that applies in one context out of ten is paying context load the nine other times.
+
+**Do I need to rewrite my documents for each new model?**
+Mostly no, and over-fitting to one model is its own trap. Updating for a new model is usually another no-op pass rather than a rewrite.
+
+**My skill only works on the exact task I built it from.**
+The common route — do the work once, then have the agent write it up as a skill — over-indexes on that one run, and the exemplars come out too specific. Keep the run as evidence, then abstract deliberately: strip what belonged to that repo and those files, and write for the class of task.
+
+**English isn't my first language. Do I lose the leading-word advantage?**
+No — finding the word that packs the most behaviour into the fewest tokens is work the reference does for you. It is one of the things it is for.
+
+## It's working if
+
+- The document gets shorter as it gets better, and you are surprised how little is left.
+- You can point at a leading word and watch it doing work in more than one place.
+- Nothing is stated twice, in any form. Duplication is the most reliable sign a document was never tested.
+- Reference that only one branch needs sits behind a pointer rather than in the main file.
 
 ## Where it fits
 
-This is a reach-for-it-anytime standalone reference — the meta-skill you consult while building the rest of the set, not a step in a chain. When you're unsure which skill or flow fits a task, [ask-matt](https://aihero.dev/skills-ask-matt) routes you over the whole set.
+This is a reach-for-it-anytime standalone reference. It has no neighbour in the chain because it sits underneath the whole set rather than beside any one skill: every skill here was written against it, and the documents the other skills leave behind — a `CONTEXT.md` and its ADRs, a spec, a ticket — are exactly the text it governs once an agent has to read them. When you're unsure which skill or flow fits a task, [ask-matt](https://aihero.dev/skills-ask-matt) routes you over the whole set.