Conciseness

The skill is quite long (~400 lines) and includes several sections that over-explain or repeat concepts Claude already knows (e.g., 'FP is a tool, not a religion', 'If your team can't read it, it's not good code', extensive 'When NOT to Use FP' section with obvious examples). The code examples are valuable but the surrounding prose and motivational framing add significant token overhead. The 'When Your Team Doesn't Know FP' section explains social dynamics Claude doesn't need.

Actionability

Every pattern includes complete, executable before/after TypeScript code examples with correct fp-ts imports. The cheat sheet provides a quick reference mapping intent to specific fp-ts functions. The code covers common real-world scenarios (JSON parsing, validation, async chains) and is copy-paste ready.

Workflow Clarity

This is primarily a reference/pattern skill rather than a multi-step workflow skill, so the simple-skill exception partially applies. The progression from basic patterns (pipe → Option → Either → map → flatMap) is logical and well-sequenced. The 'When to Level Up' section provides clear ordering. Minor gap: no explicit guidance on how to incrementally adopt these patterns in an existing codebase (e.g., start with X, then refactor Y).

Progressive Disclosure

All content is inlined in a single monolithic file with no references to supporting files. At ~400 lines, the 'Common Refactors' and 'Quick Wins' sections could reasonably be split into separate reference files. The 'When to Level Up' section mentions TaskEither, Validation, Reader, and Do notation but doesn't point to any detailed guides. The internal structure (headers, sections) is good, but the file is too long for a single SKILL.md.

Specificity

Names the domain (fp-ts functional programming in TypeScript) but provides no concrete actions. Phrases like 'practical, jargon-free guide' and '80/20 approach that gets results' are vague fluff without specifying what the skill actually does (e.g., compose pipelines, handle Option/Either types, use TaskEither).

Completeness

Has a 'what' (guide to fp-ts functional programming) and an explicit 'when' clause ('Use when writing TypeScript with fp-ts library'). However, the 'what' is vague—it describes a philosophy ('jargon-free', '80/20 approach') rather than concrete capabilities, and the 'when' could be more specific about trigger scenarios.

Trigger Term Quality

Includes relevant keywords like 'fp-ts', 'TypeScript', and 'functional programming' which users would naturally mention. However, it misses common trigger terms like specific fp-ts constructs (Option, Either, pipe, TaskEither, io-ts), or phrases like 'monads', 'error handling with fp-ts', or 'functional composition'.

Distinctiveness Conflict Risk

The mention of 'fp-ts' specifically is quite distinctive and unlikely to conflict with general TypeScript or other functional programming skills. Minor overlap risk exists with broader TypeScript coding skills or general functional programming guides.