Conciseness

The body is dense with Luzmo-specific facts Claude cannot know (sandbox CSP allowlist, 10 MB/1 MB/5 KB size limits, 9-position slot budget, Update-in-preview publish flow) and assumes programming competence throughout, matching the 'efficient; minor instances that could be trimmed' anchor. It falls short of anchor 5 because of some redundancy: the exclusion list appears in both the description and the 'This skill does NOT cover' block, and 'Doc Retrieval' overlaps 'Required Docs'/'Canonical Sources'.

Actionability

Guidance is fully concrete and executable: exact commands ('npm run build', 'npm run validate', 'npm run charts -- upload'), a copy-paste HTML embed snippet, the exact ChartParams destructure list, snake_case column_id/dataset_id fixes, multipart/form-data API payloads with properties.status=published, and concrete mistake→fix and problem→cause→solution tables covering common cases. Nothing is pseudocode or hand-wavy.

Workflow Clarity

The 7-step Development Workflow is clearly sequenced with an explicit validation step (build/validate before upload), a STOP-gated security checklist ('If ANY checkbox is unchecked, STOP and fix'), a destructive-operation guard (no re-upload over an existing chart id without explicit user approval), and feedback loops via the Troubleshooting table and post-publish MCP testing. This matches the anchor-5 pattern of sequence plus checkpoints plus error recovery.

Progressive Disclosure

Structure is good: a verified, clearly-signaled one-level-deep reference (references/chart-development.md, listed under 'Bundled References' with its scope), external canonical doc URLs, and the explicit rule 'If content exists on developer.luzmo.com, link - do not duplicate specs here'. It stays at anchor 4 rather than 5 because the body itself runs ~165 lines with substantial detail (Manifest and Runtime Essentials, rules, troubleshooting) that overlaps what the reference file re-covers, so the split between overview and reference is not as clean as it could be.

Specificity

The capability statement 'Build a brand-new Luzmo chart component when no built-in chart type (and Flex) is sufficient' names a concrete primary action, and the trigger list explicitly enumerates further specific actions ('upload custom chart', 'publish custom chart', 'custom chart CSV/Excel export', 'custom chart options in Edit item panel'), matching the 'several specific actions with minor gaps' anchor. It does not reach anchor 5 because the full authoring pipeline (manifest configuration, implementing render/resize, build) is only alluded to via function names rather than stated as capabilities.

Completeness

Both questions are explicitly answered: the 'what' ('Build a brand-new Luzmo chart component...') and the 'when' via a dedicated 'Triggers on:' clause with concrete trigger phrases, plus an explicit rarity signal ('Rare advanced path (~95% of users never need this)'). This matches the anchor-5 example structure of capability statement followed by concrete 'use when' triggers exactly.

Trigger Term Quality

The trigger list is comprehensive and natural: 'custom chart', 'build a custom chart', 'chart plugin', 'custom chart not in picker', 'upload custom chart', 'publish custom chart', 'custom chart CSV/Excel export', 'slot position' — covering synonyms, action phrasings, and symptom phrasings a user would actually say. It fits the 'comprehensive coverage of natural terms including synonyms' anchor rather than anchor 4, since no common variation of the request is obviously missing.

Distinctiveness Conflict Risk

The description carves a clear niche (custom chart component authoring only when built-in types and Flex are insufficient) and explicitly de-conflicts with four sibling skills ('Not for Flex charts with built-in types (use data-visualization), embedding saved dashboards (use core), self-service chart editors (use analytics-studio), or auth setup (use core)'). This exceeds anchor 4's 'minor overlap risk'; the only slight blemish is the bare generic word 'manifest' as a trigger, but the surrounding scoping keeps conflict risk minimal.