Mostly efficient but includes some unnecessary explanation. The 'Why all three?' section is somewhat verbose explaining things Claude would understand, and 'The Problem' section restates what the description already covers. The 'Code after yield runs on shutdown...' explanation is borderline but useful for a nuanced behavior.

Fully executable code throughout — error classes, exception handlers, route usage, and lifespan shutdown are all copy-paste ready. The 'Applying to Existing Code' section gives concrete search-and-replace steps. Every code block is complete and runnable.

Clear numbered sequence (define errors → register handlers → use in routes → add shutdown). The 'Applying to Existing Code' section provides a clear migration workflow. The checklist at the end serves as a validation checkpoint. The skill doesn't involve destructive operations, so the level of validation is appropriate.

The content is well-structured with clear sections, but it's somewhat long for a single SKILL.md file. The error response format examples, the detailed 'Why all three?' explanation, and the migration checklist could potentially be split into referenced files. The verifier references at the bottom are good but the main content is monolithic.

Lists multiple specific concrete actions: exception handlers, structured error responses, async error patterns, and graceful shutdown. These are distinct, well-defined capabilities.

Clearly answers both what ('exception handlers, structured error responses, async error patterns, and graceful shutdown') and when ('when building or reviewing FastAPI backends, when you see unhandled exceptions returning raw 500s, or when error response formats are inconsistent') with explicit trigger scenarios.

Includes strong natural trigger terms users would say: 'FastAPI', 'exception handlers', 'error responses', 'unhandled exceptions', 'raw 500s', 'error response formats', 'async error patterns', 'graceful shutdown'. These cover common ways developers describe these problems.

Highly distinctive — scoped specifically to FastAPI error handling in production contexts. The combination of framework (FastAPI), concern (error handling), and specific symptoms (raw 500s, inconsistent error formats) makes it unlikely to conflict with general Python, general error handling, or other web framework skills.