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

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context7-websites-code-claude claude-code-subagents-docs context7-github-en-copilot github-custom-agents-configuration

Agent Description Quality Reference

Upstream source: Claude Code subagent reference, GitHub Copilot custom-agents configuration. House contract: ADR-0020, the context budget. The house contract is narrower than either platform's schema 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 and agent. The body is never seen until the agent is invoked. The description therefore carries the entire triggering burden and is paid for in every session, whether the agent 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 caller 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 or user-invocable: false — the agent 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 agent 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 agent is a wrong finding, not a strict one. Both fields are Copilot-only and neither is on the vendor-neutral APM allowlist, so this case arises in a Copilot .agent.md at project/user scope and nowhere else. Its Claude Code counterpart has no equivalent field and stays model-invoked, so the two halves of the pair carrying differently shaped descriptions is expected there rather than a pair-consistency finding.
• No such flag — the agent 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 agent ... — the caller 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.

Everything else belongs in the body or in the plugin's 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 an agent whose domain word is unavoidable is padding charged to every session.

Near-miss exclusions

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

Before / after

# FAIL — a noun-phrase opener rather than a trigger, capability enumeration in
# place of one capability clause, and no boundary clause at all, preloaded into
# every session forever. (The live git-orchestrate description, 254 chars.)
description: Orchestrates git workflow operations for other agents. Invoke when a
  caller needs a multi-step or destructive git operation (rebase, force-push, branch
  deletion) coordinated across domain skills with safety gates, session context, and
  structured results.

# PASS — trigger, one capability clause, boundary. The operation list and the
# safety-gate mechanics are the body's job; the router cannot act on them.
description: >
  Use when an agent caller needs a multi-step or destructive git operation
  dispatched and safety-gated. Not conversational git help -> git-workflow.

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. Agent descriptions have no platform-documented ceiling of their own — unlike a skill's 1,024-character spec limit, the 400-character house ceiling is the only hard limit there is, so do not go looking for a backstop behind it.

• 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 agent", "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 agent ..., This is the ...). Kyberforge.DescriptionOpener catches any opener matching ^This. There is no action-verb rule here and never was a defensible one: an Orchestrates ... or Audits ... opener is a catalogue entry, not a trigger.

• Vague capabilities ("helps with agents" where "audits an agent definition pair" 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. No script checks this for an agent file — validate.sh resolves boundary targets for skills only, so resolve the name yourself against plugins/*/.apm/skills/ and plugins/*/.apm/agents/.

• Use proactively in a Copilot or vendor-neutral description. KyberforgeCopilot.ProactivePhrase catches it. The phrase steers the Claude Code runtime and does nothing anywhere else, so in a .agent.md it is preloaded text that buys no behaviour.

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

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.