Lists multiple specific concrete security features: CORS, HTTPS redirection, HSTS, security headers, rate limiting, anti-forgery, authentication, authorization, Data Protection API, input validation, and Content Security Policy.

Clearly answers both what (security defaults including CORS, HTTPS, HSTS, etc.) and when ('whenever you create or modify any ASP.NET Core app', 'If you are writing builder.Services.AddControllers()'). Explicit trigger guidance is provided.

Includes technical terms like 'ASP.NET Core', 'CORS', 'HSTS', 'security headers' which are relevant but may miss natural user phrases like 'secure my app', 'add security', or 'protect my API'. The trigger 'builder.Services.AddControllers()' is very specific but narrow.

Highly distinctive with clear niche: ASP.NET Core security specifically. The combination of framework-specific terminology and comprehensive security feature list makes it unlikely to conflict with general security or other framework skills.

The skill is comprehensive but includes some unnecessary explanation (e.g., 'the same way you would not ship a car without seatbelts' analogy, repeated emphasis that these are mandatory). The WRONG/RIGHT pattern is useful but adds length; some sections could be tightened.

Excellent actionability with fully executable, copy-paste ready code examples for every security feature. Each section shows both wrong and right approaches with complete, working C# code including proper using statements and configuration.

Clear middleware pipeline order section explicitly shows the correct sequence. The checklist at the end provides validation checkpoints. Each section has clear before/after patterns showing what to avoid and what to implement.

The skill is a monolithic document (~500 lines) that could benefit from splitting detailed sections (like CSP configuration, FluentValidation setup) into separate reference files. The verifiers section at the end references external files, but the main content is all inline.