Conciseness

The body is largely dense and efficient — categorization and detection-model tables, four complete query examples, a repo layout, and a CI checklist with specific commands. It is not a 5 because a few tokens don't earn their place: conversational asides ("future-you will thank you", "pays for itself the first time someone asks 'what do we detect?'") and a definitional sentence Claude doesn't need ("Sigma is the cross-SIEM detection format"). It sits above the score-3 anchor because these are minor trims, not whole padded sections.

Actionability

Guidance is fully executable throughout: complete Sigma, KQL, SPL, and ES|QL rule examples that are copy-paste ready, concrete CI commands ("sigma-cli check", "sigma convert -t splunk"), a directory layout for detections-as-code, and a filled-in coverage-assessment output template. This matches the score-5 anchor 'fully executable; copy-paste ready code or commands; specific examples cover the common cases' and exceeds the score-4 anchor, which allows minor gaps — none are apparent.

Workflow Clarity

The six-step methodology is clearly sequenced with explicit validation checkpoints and feedback loops: a gap check before writing any rules ("Techniques with NO source mapped are blind spots — write them down before writing any rules"), the experimental-to-production tuning lifecycle with an FP-ratio check ("if FPs are > 80% after tuning, the detection model is wrong"), verification of never-fired rules via "a deliberate-test event through the system," and error recovery ("Roll back via Git revert"). This matches the score-5 anchor; no validation gaps significant enough to fall to 4.

Progressive Disclosure

As a single-file skill with no bundle files, the content is well organized under clear section headers (Authorization, Scope, Methodology steps, Output Format, Boundaries, References) with nothing buried or nested — good structure with most content appropriately placed. It falls short of 5 because the skill is long (~240 lines) and the per-backend query examples (KQL, SPL, ES|QL) plus the general References list would sit more naturally in one-level-deep reference files, and the References section names resources without links; these are minor organization gaps fitting the score-4 anchor rather than the score-3 'content that should be separate is inline' anchor, since what remains inline serves the core workflow.

Specificity

The description lists multiple concrete actions with comprehensive coverage: "Engineer and audit SIEM detection rules — log source coverage, Sigma / KQL / SPL / Elastic query authoring, MITRE ATT&CK mapping, false-positive tuning, and detection-as-code workflows." It matches the anchor 'lists multiple specific concrete actions; comprehensive coverage' — the actions are named and complete for the domain, so it does not fall to the score-4 anchor with coverage gaps.

Completeness

It explicitly answers both questions: a clear 'what' ("Engineer and audit SIEM detection rules — ... false-positive tuning, and detection-as-code workflows") and an explicit 'when' with concrete trigger phrases ("Use when the user mentions 'SIEM,' ... or needs help building or improving security detections."). This is a direct match for the score-5 anchor; a missing or weak 'Use when' clause would have capped it at 3, but the trigger guidance is fully explicit.

Trigger Term Quality

The trigger clause covers natural terms comprehensively, including synonyms and platform names users actually say: "'SIEM,' 'detection engineering,' 'detection rules,' 'Sigma,' 'KQL,' 'SPL,' 'Splunk,' 'Sentinel,' 'Elastic,' 'Wazuh,' 'Chronicle,' 'detection-as-code,' 'MITRE ATT&CK mapping,' 'log coverage,' 'alert tuning,' 'use case development.'" This matches the anchor 'comprehensive coverage of natural terms including synonyms' and clearly exceeds the score-4 'a few natural terms missing' anchor.

Distinctiveness Conflict Risk

The detection-engineering niche is clear and terms like 'Sigma,' 'detection-as-code,' and 'MITRE ATT&CK mapping' are unambiguous triggers. However, the list also includes bare platform names — 'Splunk,' 'Sentinel,' 'Elastic,' 'Wazuh,' 'Chronicle' — that a user could mention for non-detection work (dashboarding, search performance, platform administration), creating minor overlap risk with closely related log-management skills. This fits the score-4 anchor ('mostly distinct; minor overlap risk with closely related skills') better than the score-5 anchor's 'minimal conflict risk,' and is well above the score-3 'could still overlap with similar skills' anchor.