Conciseness

The body is dense and prescriptive, carrying almost exclusively project-specific rules Claude could not infer (the word-ceiling table of 100/250/500, bus file clearing protocol, slug resolution order) rather than explanations of known concepts. Minor trimmable over-explanation remains — the "Wording" and "Form" bullets restate general style advice ("Use everyday words, concrete subjects and active verbs", "Put commands in code blocks") Claude already follows — so it fits anchor 4 rather than the every-token-earns-its-place bar of 5.

Actionability

Guidance is concrete and executable throughout: numeric reply ceilings (100/250/500 words), exact paths and file names (".apm/bus/", "task.md", "report.md", "handoff.md", "manager/"), a worked invocation example ("`apm-5-check-reports frontend-agent` in the Manager's chat"), and an ordered matching procedure ("an exact match first, then a prefix, then the closest plausible name"). It is not 5 because there is no worked example of ID resolution matching or a sample bus message, and formats are deferred to role guides — appropriate, but it leaves minor gaps.

Workflow Clarity

The bus protocol is an explicitly sequenced workflow with verification ("Read a bus file before writing it... verify the written content before announcing it", "After you process an incoming message, clear its file before you write your outgoing one"), reply drafting has a checkpoint ("check that it opens with the substance and fits its ceiling"), and ID resolution has ordered fallbacks with User confirmation. It is not 5 because there is no error-recovery loop when verification fails, and section 2 is a convention list rather than a sequenced process. No destructive or batch operation is involved, so no cap applies.

Progressive Disclosure

The ~50-line body is cleanly sectioned (1/2/3 with 3.1/3.2) with no inlined bulk that belongs elsewhere, and the single deep-dive topic is split out to a clearly signaled, one-level-deep reference ("{SKILL_DIR:apm-communication}/bus-integration.md describes how"). No bundle directories (references/, scripts/, assets/) are provided — the bundle is SKILL.md alone — so per the simple-skill guideline the well-organized structure with its one clearly signaled external reference earns the top score.

Specificity

The description names its domain ("APM agents", "file-based Message Bus") and identifies three write targets ("to the User, to each other and through the file-based Message Bus"), but the only action is the generic verb "write" — no concrete artifacts such as Task Prompts, Task Reports or Handoffs are named. It sits between anchor 2 (generic actions) and anchor 3 (domain plus 1-2 concrete actions); the three distinct channels lift it just to 3, and it is not 4 because no specific capabilities are enumerated.

Completeness

"How APM agents write to the User, to each other and through the file-based Message Bus" answers "what" clearly, but there is no "Use when..." clause or equivalent trigger guidance anywhere, which the rubric explicitly caps at 3. It is not 2 because the "what" is concrete and domain-specific rather than vague.

Trigger Term Quality

"Message Bus" and "APM agents" are relevant domain keywords a practitioner in this ecosystem would say, but common natural variations are missing — "task prompt", "task report", "handoff", "reply to the user", "communicate". This matches anchor 3 ("Some relevant keywords but missing common variations or synonyms"); it is above 2 because the terms present are specific rather than generic filler.

Distinctiveness Conflict Risk

"APM agents" and "file-based Message Bus" carve a clear niche that unrelated skills are unlikely to trigger, fitting anchor 4 ("Mostly distinct; minor overlap risk with closely related skills") given sibling APM guides that also involve writing files. It is not 5 because the description offers no explicit distinct triggers and relies on domain terms alone.