Conciseness

The core pattern examples are efficient and earn their tokens, but there is padding Claude does not need: three long 'MESSY' try/catch anti-example blocks (processOrder, processUserOrder, loadDashboard) demonstrating what bad code looks like, a basic explanation of what Either/Left/Right means, a duplicated processUserOrder (both nested-chain and Do-notation versions), and a Quick Reference table recapping operations already shown. Mostly efficient with clear trimming opportunities, rather than noticeably below the midpoint.

Actionability

The body provides concrete, mostly copy-paste-ready TypeScript across all sections. Minor gaps keep it from fully executable everywhere: several functions are stubs with '{ ... }' bodies (getUser, getProduct, createOrder, validateInput), the processAllCollectErrors example uses O.some/O.none without importing O, and validateForm reads form.email off a FormData object as though it were a plain record. This matches mostly executable guidance with minor gaps.

Workflow Clarity

This is a pattern-reference skill with no destructive or batch operations performed by the skill itself, so no validation checkpoints are required; the content is clearly and progressively sequenced (problem → pattern → variants → boundary conversion → real scenarios → quick reference → summary) and each pattern is unambiguous. Minor gaps remain, such as no guidance on when to prefer Do notation over nested E.chain, keeping it below the top anchor.

Progressive Disclosure

The actual bundle contains no reference, script, or asset files — everything is inlined in a single ~850-line SKILL.md. Internal structure is good (clear headers, Quick Reference table, Summary), but content that plausibly belongs in separate files (Real Scenarios, the TaskEither/retry deep-dive) is inline, and the under-50-lines exception for single-file skills does not apply at this length. This fits the anchor for good structure but with content that should be separate kept inline.

Specificity

The description names the domain and two concrete constructs ("using fp-ts Either and TaskEither") but offers only one action ("Handle errors as values") without listing several specific actions such as wrapping throwing code, chaining async operations, or accumulating validation errors. It matches the anchor for naming the domain with 1-2 concrete actions but not comprehensive coverage, rather than the level above which requires several listed actions.

Completeness

Both what ("Handle errors as values using fp-ts Either and TaskEither for cleaner, more predictable TypeScript code") and when ("Use when implementing error handling patterns with fp-ts") are explicitly present. The 'when' clause is nearly tautological with the 'what' and could be more specific about concrete trigger situations, which fits the anchor for both present but 'when' needing more explicitness rather than the top anchor with concrete trigger phrases.

Trigger Term Quality

Natural terms a user would say are present: "error handling", "fp-ts", "Either", "TaskEither", "TypeScript". A few natural variants are missing (e.g., "Result type", "functional error handling", "replace try/catch"), which matches good-but-not-comprehensive keyword coverage rather than the comprehensive-with-synonyms anchor.

Distinctiveness Conflict Risk

"fp-ts Either and TaskEither" carves out a clear niche with distinct triggers; virtually no other skill would match these terms. Minimal conflict risk, matching the top anchor for a clear niche with distinct triggers.