holocron/plugins/kyberforge/skills/skill-audit/references/description-quality.md

source_keys

source_keys
agentskills-spec agentskills-optimizing-descriptions

Description Quality Reference

Upstream source: agentskills.io — optimizing-descriptions, specification. House contract: ADR-0020, the context budget. The house contract is narrower than the spec rather than a reinterpretation of it: where both speak, both must be satisfied.

Why the description is the expensive part

At startup an agent loads only the name and description of every installed skill. The body is never seen until the skill triggers. The description therefore carries the entire triggering burden and is paid for in every session, whether the skill fires or not.

A second cost is less obvious and is a correctness hazard rather than a token cost: a description that summarises the workflow is a shortcut the agent takes instead of reading the body. A measured failure upstream — a description saying "code review between tasks" — produced one review where the body's flowchart specified two.

Step 0 — establish which contract applies

Read the frontmatter before judging a single word.

• disable-model-invocation: true — the skill is hand-invoked. Its description is never matched against user intent, so it is not a routing string. It carries one plain human-facing sentence stating what the skill does. Audit it for that and nothing else. Reporting a missing trigger clause, a missing boundary clause or absent indirect triggers on a hand-invoked skill is a wrong finding, not a strict one.
• No such flag — the skill is model-invoked and the rest of this file applies.

The three-part shape

A model-invoked description carries exactly three things:

1. Trigger clause. When to invoke, phrased imperatively: Use when .... Not This skill ... — the agent is deciding whether to act, not reading a catalogue entry.
2. At most one capability clause. What it does, in one clause. Never an enumeration.
3. Boundary clause. Compressed form: Not <thing> -> <skill-name>. The target must resolve to a real skill directory or agent file in the authoring source; validate.sh checks that deterministically and a dangling target already surfaces as a Structure FAIL.

Everything else belongs in the body or in README.md.

Indirect triggers — conditional, never blanket

Add "even if the user doesn't say X" only where the user's natural phrasing genuinely omits the domain word. True for the gitea-* family: people say "create an issue", not "create a Gitea issue". False for git-commits: nobody asks for a commit without saying commit. A blanket indirect-trigger clause on a skill whose domain word is unavoidable is padding charged to every session.

Near-miss exclusions

Add a boundary clause only where a sibling skill could plausibly steal the activation. Use strong near-misses — queries that share keywords but need something different — not weak ones ("write a fibonacci function"). One boundary clause per genuine near-miss; a list of four is enumeration wearing a boundary's clothes.

Before / after

# FAIL — enumeration first, mechanics as the opener, a blanket indirect trigger,
# and 300+ characters of it preloaded into every session forever.
description: >
  Analyze CSV and tabular data files — compute summary statistics, add derived
  columns, generate charts, and clean messy data. Use when the user has a CSV,
  TSV, or Excel file and wants to explore, transform, or visualize the data,
  even if they don't explicitly mention "CSV" or "analysis."

# PASS — trigger, one capability clause, boundary. The four verbs the FAIL
# version enumerates are the body's job; the router cannot act on them.
description: >
  Use when the user has a CSV, TSV, or Excel file and wants it explored,
  transformed, or charted. Not schema design -> data-model.

(data-model is illustrative. In a real description the target has to resolve.)

Auditing guidance

Flag as FAIL if:

• Over 400 characters. Measured on the folded YAML value, not the raw source lines. validate.sh reports the number; do not re-derive it, but do point the Fix at what to cut.

• Internal mechanics appear in the description. Any of:

  • capability enumeration or a feature list;
  • output-format detail ("Produces a compact findings report with Why and Fix per finding");
  • composition or architecture notes ("composes X rather than duplicating Y", "a cross-cutting shared skill", "the human-facing entry point", "replaces the old flat invocation");
  • implementation detail ("self-validates via a bundled deterministic script").

  None of it can change a routing decision and all of it is preloaded. Kyberforge.CompositionNote catches the common phrasings deterministically; the rest is judgment. This is the rule that deflates a description, so apply it before reaching for length.

• The same trigger stated twice in two registers — a verb list, then the same verbs re-quoted as user phrasings, usually in the same order. One register, whichever routes better.

• Descriptive rather than imperative phrasing (This skill ..., This is the ...). Kyberforge.DescriptionOpener catches any opener matching ^This.

• Vague capabilities ("helps with APIs" where "parses and validates OpenAPI specs" was available). Kyberforge.VagueWording catches the known filler; imprecision outside that list is judgment.

• A boundary clause naming a target that does not resolve to a real skill directory or agent file in the authoring source. validate.sh reports the unresolved name.

• Trigger-list, boundary or indirect-trigger content on a hand-invoked skill — see Step 0.

• Over 1024 characters — the agentskills.io specification ceiling, unchanged and independent of the 400-character house ceiling above.

Flag as SUGGESTION if:

• Over 250 characters but at or under 400. This tier is what moves the corpus average; the FAIL tier only stops outliers. Report it rather than treating a 399-character description as clean.
• A near-miss exclusion is present but targets a weak near-miss.
• An indirect trigger is present and warranted but could name the omitted phrasing more precisely.