Conciseness

The body defers all per-verb detail to "slack --help" and every rule carries only operational facts (keyed refusals, exit codes, the 12,000-character cap, mrkdwn escaping). No concept Claude already knows is explained and no section is padded — every token earns its place.

Actionability

The opening block gives a complete executable CLI synopsis with every flag for all six verbs, and rules name concrete commands ("run `slack setup` for each bound root", "`lane-mail send --delivery-id`") plus concrete outcomes (`text-too-long`, exit 0, exit 2). This is copy-paste-ready guidance covering the common cases, matching the 5 anchor; it is not a 4 because no guidance is merely high-level.

Workflow Clarity

The setup → listen → post sequence is clear from the synopsis and Rules, and validation exists via "slack listen --status" with "state=ok|failing|stale|never" and `fix=` plus retry-on-next-poll and `already_reacted` settlement. It is not a 5 because the checkpoints are scattered across rules rather than laid out as a sequenced flow with feedback loops, and not a 3 because explicit status/validation and error-recovery behavior are present.

Progressive Disclosure

Sections (Rules / Message standard / Doctor row) are well organized, references are clearly signaled with section anchors, and the primary disclosure runs through the real `scripts/slack` entry point. It is not a 5 because two referenced paths — [schemas/journal.md](schemas/journal.md) and [kendex.settings.toml.example](kendex.settings.toml.example) — do not exist in the provided bundle, and detailed output-format specs (the `read` line format, doctor row fields) are inlined rather than split out.

Specificity

"bind an overseer's mailbox to a private Slack channel, run or check the relay, or post an alert or a file to Slack" lists several concrete actions (bind, run, check, post alert, post file). It falls short of the 5 anchor because the read, compact and install capabilities from the CLI are not represented in the description.

Completeness

The "what" is answered concretely with multiple actions, and the "when" is present via the explicit "Load to..." trigger construction enumerating each situation. It is not a 5 because there is no separate "Use when the user mentions/asks..." clause making the trigger conditions fully explicit, and not a 3 because equivalent explicit trigger guidance is stated.

Trigger Term Quality

"Slack", "private Slack channel", "relay", "post", "alert" and "file" are natural terms a user would say when needing this skill. It is not a 5 because common variations such as "send", "message" or "notify" are missing.

Distinctiveness Conflict Risk

The niche is clear and distinctive: relaying "an overseer's mailbox to a private Slack channel" with "Slack" as the trigger term. Minimal overlap risk with any generic skill; no other skill would trigger for these requests.