Lists multiple specific concrete actions: 'structures and derives research formulas', 'build a theory line', 'organize assumptions', 'turn scattered equations into a coherent derivation', 'rewrite theory notes into a paper-ready formula document'. These are concrete, actionable capabilities.

Clearly answers both 'what' (structures and derives research formulas, organizes assumptions, turns scattered equations into coherent derivations) and 'when' (explicit 'Use when' clause specifying conditions: derivation target not fully fixed, main object needs choosing, user needs a derivation package rather than a finished proof).

Includes strong natural trigger terms: '推导公式' (Chinese for derive formulas), 'build a theory line', 'organize assumptions', 'scattered equations', 'coherent derivation', 'paper-ready formula document', 'derivation target', 'theorem proof'. Good coverage of terms a researcher would naturally use, including bilingual triggers.

Occupies a clear niche: research formula derivation and structuring, distinct from general math solving, theorem proving, or paper writing. The explicit contrast with 'finished theorem proof' helps disambiguate from adjacent skills. The bilingual trigger '推导公式' further narrows the scope.

The skill is fairly long (~200+ lines) and some sections could be tightened—e.g., the detailed enumeration of derivation types (identity/proposition/approximation/interpretation) is repeated multiple times across Steps 5, 7, and 8. However, most content is domain-specific guidance that Claude wouldn't inherently know, so it's not padding with basic concepts. It's mostly efficient but has redundancy.

The skill provides highly concrete, step-by-step instructions with specific file structures, exact status labels, explicit decision criteria (e.g., when to downgrade to blocker report), a complete markdown template for the output document, and clear trigger phrases for when to use this skill vs proof-writer. Every step tells Claude exactly what to do.

The 8-step workflow is clearly sequenced with explicit validation checkpoints (Step 2 freezes the target before manipulation begins, Step 8 is a comprehensive verification checklist with feedback loop—downgrade status if verification fails). The workflow handles error cases (incoherent derivation → blocker report) and has clear decision points throughout.

The content is well-organized with clear sections and headers, but it's a monolithic document with no references to supporting files despite being quite long. The required file structure template, output modes, and relationship to proof-writer could potentially be split into separate reference files. However, for a standalone skill with no bundle, the internal organization is reasonable.