Conciseness

The 588-line body is noticeably verbose: the expected-results table's Why column ('Each witness is a state that must be reachable: a create that gave up recorded the session destroyed, gc removes a session, a session serves, a resize lands...') runs to thousands of words in table cells, and the 'Races the guards prevent' narratives plus paragraph-length Scope bullets re-explain much of the same guard and race content. Not a 3: the duplication across the table, the races section, and Scope is substantial rather than a few spots to tighten; not a 1: nothing explains concepts Claude already knows and there is no filler — every section is project-specific and load-bearing.

Actionability

Fully executable throughout: the exact run command ('.agents/skills/verify-session-lifecycle/scripts/check.sh'), tunables ('CHECK_JOBS=79', 'JAVA=/path/to/java', 'TLA2TOOLS_JAR=...', 'CHECK_OUT=<folder>'), exit-code semantics (0/1/2/3 with 'When both 1 and 3 apply, the exit code is 1'), and copy-paste-ready replay blocks with setup and cleanup ('.agents/skills/verify-agent-tty/scripts/cleanup.sh "$ENV_FILE"'). Specific examples cover the common cases; not a 4 because no key detail is missing.

Workflow Clarity

Multi-step processes are explicitly sequenced with validation checkpoints and feedback loops: run → interpret via exit codes and the expected-results table → 'Bug or modeling error' decision flow (map each step to code, replay with replay-hold.mjs, then 'If a step cannot happen in the code, the model is wrong... do not weaken a rule') → the numbered 'When you change covered code on purpose' procedure that requires breaking a guard once and confirming a run turns 'UNEXPECTED' before updating coverage.json. Not a 4: checkpoints are explicit, including error recovery and drift handling ('A guard reads FALSE when its condition text... differs... That is drift in the check, not a bug').

Progressive Disclosure

There is real structure — clear section headers, a 'Files' section, and genuinely external scripts (scripts/check.sh, scripts/facts.mjs, scripts/replay-hold.mjs all exist in the bundle) — but hundreds of lines that clearly belong in separate reference files are inlined: the ~20 'Races the guards prevent' narratives with full replay transcripts, the giant expected-results table, and the Scope assumptions all live in SKILL.md, and the referenced model/SessionLifecycle.tla, model/statechart-view.mjs and coverage.json are absent from this bundle. Not a 4: the bulk of the detail is inline rather than one level deep; not a 2: sections are well-organized and the operational scripts really are external, so it is not a monolith.

Specificity

Capability coverage is comprehensive and concrete — 'create, the session host (start-up, resize, destroy, SIGTERM shutdown, exit), reconcileSession (list, inspect, destroy, gc), gc and destroy (with and without --force)' — which matches the 5 anchor, but the rubric's voice rule costs one point for the second-person trigger phrasing 'Use it before you change src/host/lifecycle.ts'. Not a 3: the actions named are specific and complete, with no generic filler.

Completeness

Both halves are explicit: what it does ('TLA+ model check of the agent-tty session lifecycle when several agent-tty processes use one Home at the same time') and when to use it ('Use it before you change [specific files]... and when you must know whether a race can...'). This matches the 5 anchor's 'concrete trigger phrases' requirement; not a 4 because the 'when' is as explicit and specific as the 'what'.

Trigger Term Quality

Triggers are the natural terms for this skill's users: named source files ('before you change src/host/lifecycle.ts, src/host/programGroup.ts... the start-up, shutdown or exit path of src/host/hostMain.ts'), command names (create, gc, destroy, list, inspect), and concern-level phrases ('whether a race can delete a session, corrupt its status, leave its program running or kill a process group that is not the session's'). Not a 4: it covers both the file-path and failure-mode vocabularies users would actually say, with no obvious synonyms missing.

Distinctiveness Conflict Risk

A clear niche — TLA+ model checking of the agent-tty session lifecycle, keyed to named source files — that no generic skill would collide with. Not a 4: the named files and race-failure phrases are triggers no other skill would claim, so conflict risk is minimal.