Lists multiple specific concrete actions and domains: SwiftUI views, iOS apps, Xcode projects, Apple platform code review, widgets, watchOS apps, visionOS builds, SwiftUI layout fixes. Also specifies coverage areas like UI patterns, app lifecycle, navigation, project structure, and platform-specific guidance.

Clearly answers both 'what' (provides modern SwiftUI-first best practices covering UI patterns, app lifecycle, navigation, project structure, platform-specific guidance) and 'when' (explicit trigger phrases and scenarios listed at the beginning). The 'Use when' equivalent is the opening sentence with quoted trigger phrases.

Excellent coverage of natural trigger terms users would say: 'create a SwiftUI view', 'build an iOS app', 'set up an Xcode project', 'review Apple platform code', 'add a widget', 'create a watchOS app', 'build for visionOS', 'fix SwiftUI layout'. Also lists platform names (iOS, iPadOS, macOS, tvOS, watchOS, visionOS) which are highly natural keywords.

Clearly scoped to Apple platform development with SwiftUI focus, distinct from general Swift language fundamentals (explicitly delineated via the reference to `swift-development` for language fundamentals). The specific platform names and SwiftUI focus create a clear niche unlikely to conflict with other skills.

The skill is generally well-structured but includes some unnecessary verbosity — the TCA section is quite long for an alternative pattern, the design token section is extensive with two full code examples, and some explanations (like 'This is the natural pattern for SwiftUI with @Observable') add little value. However, it mostly avoids explaining concepts Claude already knows and delegates fundamentals to the swift-development skill.

The skill provides fully executable Swift code examples throughout — Observable model + view pattern, MVVM with state management, TCA reducer, environment-based DI, design tokens. All code is copy-paste ready with realistic patterns, not pseudocode. The naming conventions table and common mistakes table provide concrete, specific guidance.

The skill provides clear architectural patterns and rules but lacks explicit multi-step workflows with validation checkpoints. For example, there's no step-by-step process for 'setting up an Xcode project' or 'adding a widget' with verification steps. The MVVM pattern shows a clear structure but doesn't include a workflow for building/validating/testing a feature end-to-end. For a skill covering project setup and multi-step operations, explicit validation steps would strengthen this.

Excellent progressive disclosure with a comprehensive reference file listing covering 16+ reference files, each clearly described with key topics. The main SKILL.md provides essential patterns inline while delegating platform-specific details, advanced patterns, and interop guides to well-organized reference files. Navigation is clear with tables mapping platforms/features to references. References are one level deep and well-signaled.