Conciseness

The body is ~44 lines with no padding: the opening paragraph conveys non-obvious, tool-specific behavior (lane inference precedence and why a finished dirty-tree session still reads as working), and every Note is an actionable specific (auto-release semantics, one-attempt policy, accepted status values, verify command). Nothing explains concepts Claude already knows, matching the 'every token earns its place' anchor.

Actionability

Fully executable, copy-paste ready: `[ -n "$CMUX_WORKSPACE_ID" ] || exit 0` guard followed by `cmux workspace status set done`, with expected output, explicit failure handling ("If the command exits non-zero ... ignore it. Do not retry"), and a verify command (`cmux workspace status`). Covers the common cases including the wrong-workspace failure mode.

Workflow Clarity

Single-task skill where the action is unambiguous, which the guidelines say can score 5: check the guard, run the command, compare against expected output, and confirm with `cmux workspace status`. This is not a destructive or batch operation, so no validation cap applies; failure behavior is explicitly specified.

Progressive Disclosure

Under 50 lines, single task, no bundle files exist or are needed; content is organized into well-labeled sections (When to invoke, Guard and command, Notes) with the overview up front. Per the guidelines, a skill of this size with no need for external references scores 5 on well-organized sections alone.

Specificity

The description gives the concrete action ("Pin the current cmux workspace to the done lane") with the verbatim command `cmux workspace status set done`, fully covering this single-action skill with no gaps. It exceeds anchor 4 ('several specific actions; minor gaps') because nothing is missing, and does not explain padding or vagueness that would lower it.

Completeness

Explicitly answers both what ("Pin the current cmux workspace to the done lane with `cmux workspace status set done`") and when ("Use at the end of a work session running inside a cmux terminal, right before the final response"), plus explicit negative triggers ("skip when work is blocked, handed off, awaiting user input, or when nothing was changed"). Matches anchor 5's requirement of concrete trigger phrases for both.

Trigger Term Quality

Good natural-term coverage within its niche: "cmux terminal", "workspace", "done lane", "session goal is reached and verified", "blocked", "handed off", "right before the final response". A few natural phrasings users might say are absent (e.g. "mark the workspace done", "finish the session"), which keeps it below anchor 5's 'comprehensive coverage including synonyms'.

Distinctiveness Conflict Risk

Clear niche: the description is tied to a specific tool (cmux), a specific subcommand, and a specific moment (end of verified session). Anchor 5 ('clear niche with distinct triggers; minimal conflict risk') fits; no generic language that would overlap with other skills.