Lean, code-driven content with no padding of concepts Claude already knows; the one context line ('Sessions persist across tool-call boundaries within the same agent's lifetime') is gateway-specific and earns its place.

Every section gives fully executable, copy-paste-ready tmux commands with inline comments (e.g. 'tmux new-session -d -s build ...'), including concrete common-pattern recipes.

The session lifecycle (start → check → send → end) is clearly sequenced, and the build pattern includes an explicit checkpoint/feedback loop ('if [ -f /tmp/build.exit ] ... else Build still running') plus a 'When NOT to use' guardrail.

A simple, single-purpose skill with well-organized sections and no nested references; no bundle files exist, so the self-contained structure satisfies the simple-skill allowance for a top score.

Lists multiple concrete actions — 'start a detached session, run a long task, reattach later, capture output' — matching the anchor for several specific concrete actions rather than merely naming the domain.

Explicitly states what it does ('Manage long-running shell sessions with tmux...') and when to use it ('Use when a task takes longer than a single tool call (build, test, log tail)'), satisfying both halves with an explicit trigger.

Includes natural terms users would say — 'build, test, log tail', 'long-running shell sessions', 'tmux' — giving good coverage rather than only some relevant keywords.

A clear niche (tmux long-running sessions) with a distinctive trigger tied to task duration; unlikely to fire for unrelated skills. Voice is third-person ('Manage...'), incurring no penalty.