Conciseness

Lean, imperative prose with no padding and no explanation of concepts Claude already knows; the few rationale sentences ("The rationale is mandatory. Without it, the parent cannot tell…") exist to secure compliance, so every token earns its place.

Actionability

Highly concrete for an instruction skill — default runners ("defaults opus, sonnet, haiku"), path template "/tmp/arena-<slug>/candidate-<n>/", "isolation: 'worktree'", "subagent_type: 'pstack:readonly-agent'", and a concrete-vs-vague rubric example — but minor gaps remain (no default N, and the "configured arena list" mechanism is unspecified).

Workflow Clarity

Six clearly sequenced phases (Frame → Fan out → Cross-judge → Pick → Graft → Verify) introduced via a todolist, with explicit validation in Phase F and feedback loops for error recovery ("either Phase A was wrong (re-frame and re-run) or… go back to Phase E"), so the batch-operation validation cap does not apply.

Progressive Disclosure

No bundle files exist and the body appropriately keeps all content inline in well-organized, clearly headed sections with no nested or buried references, which is the right structure for a skill of this size.

Specificity

Names the domain and several concrete actions — "Spawn N parallel candidates at the same task, pick a base, graft the strongest parts of the losers into it" — but the action list has minor gaps (e.g., the verify/synthesis-note outputs from the body are absent).

Completeness

Explicitly answers both what ("Spawn N parallel candidates… pick a base, graft…") and when ("Use for /arena, 'arena this', 'throw it in the arena', or when…") with concrete trigger phrases, matching the top anchor's structure.

Trigger Term Quality

Includes a literal command ("/arena"), natural phrases ("'arena this'", "'throw it in the arena'"), and a situational trigger ("when one attempt at a non-trivial artifact would lock in the wrong shape"), but coverage is one word-family with a few natural variants (e.g., parallel attempts, try multiple approaches) missing.

Distinctiveness Conflict Risk

Occupies a clear niche (parallel candidate generation and synthesis) with distinctive triggers like "throw it in the arena" that no other generic skill would claim, so conflict risk is minimal.