holocron/plugins/kyberforge/skills/skill-author/references/contract.md

source_keys

source_keys
agentskills-spec agentskills-best-practices agentskills-optimizing-descriptions

The description and body contract

House contract, set by ADR-0020. Every rule here is enforced by /skill-audit — scripts/validate.sh for the counts and the boundary targets, the bundled Vale styles for the prose patterns, and its reference files for the judgment calls.

Why the budget exists

A skill's name and description are loaded into every agent's context at the start of every session, whether or not the skill is ever invoked. The body is loaded only on invocation, and then competes with the caller's live conversation. Those are two different costs, so they get two different ceilings — and a fat description is not merely expensive. A description that summarizes the workflow gets followed instead of the body: a description saying "code review between tasks" produced one review from a skill whose flowchart specified two.

Description

A description carries exactly three things:

1. Trigger clause — when to invoke, imperative: "Use when ...", never "This skill ...". Focus on user intent, not the skill's internal mechanics.
2. At most one capability clause — what it does, one clause, no enumeration. Be specific ("parses and validates OpenAPI specs", not "helps with APIs").
3. Boundary clause — form: Not <thing> -> <skill-name>. Add one only where a near-miss skill could steal activations.

Banned from a description; move it to the body or to README.md:

• Capability enumeration or feature lists
• Output-format detail ("Produces a compact findings report with Why and Fix per finding")
• Composition or architecture notes ("composes X rather than duplicating Y", "This is a cross-cutting shared skill", "the human-facing entry point")
• Implementation detail ("Self-validates via a bundled deterministic script")
• Restating the same trigger twice in two registers — a verb list, then the same verbs re-quoted as user phrasings. This is a FAIL, not a suggestion.

Indirect triggers are conditional, not mandatory. Add "even if the user doesn't mention X explicitly" only where the user's natural phrasing genuinely omits the domain word — true for the gitea-* family, because people say "create an issue" rather than "create a Gitea issue"; false for git-commits, where the user says "commit". Adding one everywhere is what inflated this corpus, and it was deleted as a blanket rule.

Boundary targets must resolve. Both forms are checked — the arrow and the prose form ("do not use for X, use y instead") — so a typo dangles either way. Targets resolve against a universe built by walking up from the SKILL.md itself: the nearest ancestor holding plugins/*/.apm/{skills,agents} (or, failing that, the nearest ancestor holding .git) contributes every skill and agent under <root>/plugins/*/, plus the skill's own apm package and the packages that package declares in apm.yml under dependencies.apm. A sibling plugin in the same monorepo therefore resolves; a skill in an unrelated repo does not. A boundary clause naming a target outside that universe sends the router nowhere and fails the audit. Check the target exists before writing it — do not invent a plausible sibling name.

That universe is the apm marketplace and stops there. A host built-in is not a routing target: /compact, /clear and /init are Claude Code slash commands with no counterpart in Copilot CLI or Codex, and .apm/ source compiles for all three, so routing to one is a portability defect. The gate is right to fail it and there is no allowlist. If a built-in genuinely needs mentioning, write it un-slashed — the `compact` built-in — which makes no routing claim and is not checked.

Length. 250 characters SUGGESTION, 400 characters FAIL, counting the frontmatter value only with YAML folding resolved. The agentskills.io 1,024-character spec limit is unchanged and sits above both. The SUGGESTION tier is the one that moves the average; treat 250 as the target and 400 as the outlier stop.

Hand-invoked skills are exempt. A skill carrying disable-model-invocation: true is absent from the model-visible listing and is reached only by the user typing /name. It takes one plain human-facing sentence — no trigger clause, no boundary clause, no indirect triggers. Worked example — the whole description of the zoom-out skill, which carries disable-model-invocation:

Tell the agent to zoom out and give broader context or a higher-level perspective. Use when
you're unfamiliar with a section of code or need to understand how it fits into the bigger
picture.

Body

The body carries the decision procedure only: ordered steps, decision branches, gates, and which reference to load when. Everything else moves to references/.

Ask of every sentence: "Would the agent get this wrong without it?" Cut anything that answers "no."

Include:

• Non-obvious sequences or ordering constraints — the agent may skip or reorder steps without this
• Domain conventions the agent cannot infer from general knowledge — the core value a skill adds
• One default per decision point, plus one escape hatch — never a menu; menus cause the agent to pause or pick arbitrarily
• Gotchas — facts that defy reasonable assumptions

Exclude:

• Concepts the agent already knows (what JSON is, how HTTP works) — tokens without behavior change
• Exhaustive option lists — pick a default; the agent does not benefit from choosing
• Steps the agent handles independently — over-specifying leads agents down unproductive paths
• Restatements of the description — it is already in context

Move to references/: lookup tables, spec restatements, output schemas, templates, example blocks, rationale prose, and any content only one branch reaches. Each reference file is self-contained for its concern, and every one is wired from the body with the literal conditional form:

The one exception, stated once so it is not re-litigated: an output schema stays in the body only when it applies to every flow and is short — roughly 50 words or less, which is the "Output format template" pattern below. An output schema that is longer than that, or that only one flow produces, moves to references/ like any other schema. No third option exists, and the two rules do not disagree.

If <condition>, read `references/<file>.md`.

A generic pointer ("see references/ for details") is a Vale error — the agent cannot act on it.

Dispatch is mandatory at two or more mutually exclusive flows. The body carries the dispatch table and the gates common to every branch; each flow gets its own self-contained references/ file. Exemplar: the apm-workflow skill — a 237-word body dispatching to 3,416 words of references. Calibrate against 237: that file's whole-file count is 304 words, and aiming at that number instead overshoots the body budget by ~30%.

Length. 600 words SUGGESTION, 900 words FAIL, counting the body only — everything after the frontmatter's closing ---.

Gotchas section

• Each entry must state a fact that contradicts a reasonable default — something the agent gets wrong by acting sensibly. "Never commit secrets" is not one; the agent already knows.
• More than five entries is a SUGGESTION — five is the guideline, not a ceiling.
• A Gotcha that paraphrases a step in the body below it is a FAIL. If the rule is already a step, it is not a gotcha.
• A Gotchas section exceeding 25% of the body is a SUGGESTION.
• Place the section near the top — a gotcha read after the mistake is worthless.

Two size gates, two measurements

Gate	SUGGESTION	FAIL	Counts
description	250 chars	400 chars	the description: value only
body	600 words	900 words	the body only, after the closing ---
spec backstop	—	1,024 chars	the description: value only
spec backstop	—	2,770 words / 500 lines	the whole file, frontmatter included

The 600/900 pair and the 2,770/500 pair are not the same measurement and must not be unified: the first is a quality gate on what the caller's context absorbs, the second a conformance backstop on the file. A skill can sit well inside one and fail the other.

When a body approaches its ceiling, relocate rather than delete — move reference material to references/<topic>.md behind a conditional trigger, and bundle repeated executable logic into scripts/ rather than reinventing it each run.

Body patterns

Default with escape hatch (not a menu):

Use <X> for <task>. For <edge case>, use <Y> instead.

Prescriptive sequence (when order is critical or fragile):

Run exactly:
```bash
<command>
```
Do not modify flags.

Checklist (multi-step workflows):

- [ ] Step 1: ...
- [ ] Step 2: ...

Dispatch table (two or more mutually exclusive flows):

| Condition | Flow | Reference |
|---|---|---|
| <condition> | <flow> | `references/<file>.md` |

Output format template (when the skill produces structured output on every flow, and the schema is roughly 50 words or less — see the exception under Body above; anything longer or flow-specific belongs in references/):

Output format:
```
<field>: <value>
```

For longer templates, place them in references/<topic>.md or assets/<name>.md and reference conditionally.

Embedding org-specific policy

If a skill encodes a rule sourced from an org convention file (e.g. core/instructions/*.md), inline that content directly into the skill (SKILL.md or a references/ file) rather than pointing to the file's path. Plugins must be self-contained and portable — the org file may not exist wherever the plugin is installed, and in this repo such files are meant to be deleted once their content is fully embedded downstream. Tag the inlined content with a source_keys entry using the same references/sources.md schema as the create flow's Step 6, noting in the Research doc: field that the source is an org convention rather than a plugin research corpus entry, so provenance survives after the source file is gone.