Conciseness

The body is lean and dense: it never explains what Slack or MCP is, and every line carries operational specifics (env vars, scopes, rate limits, tool signatures, polling constants). It assumes Claude's competence, matching the anchor-5 example of every token earning its place.

Actionability

Guidance is concrete and executable for an instruction-only skill: named tools with parameter lists ('conversations_add_message — channel_id, payload, content_type, thread_ts'), required env vars, an exact message format ('⏳ Approval Required — TAS-42: <action>'), and explicit error checking ('Check the response for ok'). It falls short of anchor 5 because the payload/content_type structure for posting is never specified, leaving the most common write operation underspecified.

Workflow Clarity

The dual-channel approval workflow is a clear numbered sequence with explicit validation (check 'ok'/'error'), a feedback loop (poll conversations_replies every 30s, match approved/yes/go vs rejected/no/stop, post confirmation back into the thread), and session-end checkpoint recovery. It sits below anchor 5 because the outcome after the 10-minute poll timeout is undefined, and validation of read results (history/replies) is implicit. This is not a destructive or batch skill, so the cap-3 rule does not apply.

Progressive Disclosure

The body is under 50 lines with well-organized sections (Setup, Rate limits, Tools, Approvals) and a single clearly-signaled one-level-deep reference to channel mappings ('.opencastle/stack/notifications-config.md'), so no discovery is possible through nested references. Per the simple-skill guideline, this warrants a 5 with no external bundle files present.

Specificity

The description names the domain ('Slack MCP integration') and several concrete actions ('post progress updates, request approvals, or read user responses'). It lists multiple specific actions but is not fully comprehensive (e.g., thread management and channel resolution are implied rather than stated), matching anchor 4 rather than 5.

Completeness

It explicitly answers both questions: what ('Slack MCP integration for agent-to-human notifications and bi-directional communication') and when ('Use when agents need to post progress updates, request approvals, or read user responses via Slack channels and threads') with concrete trigger phrases, matching anchor 5. The 'Use when...' clause is present, so the completeness cap does not apply.

Trigger Term Quality

Natural terms like 'Slack', 'notifications', 'progress updates', 'approvals', and 'channels and threads' cover the phrases a user would say when needing this skill. A few common variations (e.g., 'ping me on Slack', 'ask me in Slack', 'get my attention') are missing, so it fits anchor 4 rather than 5.

Distinctiveness Conflict Risk

'Slack MCP integration' carves out a clear niche with distinct triggers (Slack-specific terms, agent-to-human notification framing); it is unlikely to trigger for an unrelated skill, matching anchor 5. Voice is third person throughout, so no penalty applies.