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tsdown

Bundle TypeScript and JavaScript libraries with blazing-fast speed powered by Rolldown. Use when building libraries, generating type declarations, bundling for multiple formats, or migrating from tsup.

68

Quality

82%

Does it follow best practices?

Impact

No eval scenarios have been run

SecuritybySnyk

Passed

No known issues

SKILL.md
Quality
Evals
Security

Quality

Content

64%

Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.

This is a comprehensive and highly actionable skill for tsdown with excellent concrete examples and good reference table organization. Its main weaknesses are excessive length (too many inline patterns that could be split into a separate file), lack of explicit build validation workflows, and a broken table in the Core References section. The content would benefit from being trimmed and restructured to keep the SKILL.md as a concise overview with patterns moved to a referenced file.

Suggestions

Move the 13+ 'Common Patterns' and 'Configuration Features' examples into a separate referenced file (e.g., references/patterns.md) to keep SKILL.md as a lean overview

Add explicit validation/verification steps to the workflow — e.g., after building, run `publint` and `attw` to verify the package is correctly structured before publishing

Fix the broken Core References table where the tsdown-migrate note interrupts the table rows (Hooks, Programmatic API, etc. are outside the table)

DimensionReasoningScore

Conciseness

The skill is fairly comprehensive but includes some unnecessary verbosity — the 'When to Use' section lists things Claude can infer, and the extensive tables and many common patterns (13+ examples) make it quite long. Some patterns like the basic library bundle are repeated from the Basic Configuration section. However, most content is reference-worthy rather than explanatory fluff.

2 / 3

Actionability

Excellent actionability with fully executable, copy-paste-ready configuration examples covering a wide range of use cases. CLI commands are concrete and specific, and every pattern includes complete TypeScript config objects that can be used directly.

3 / 3

Workflow Clarity

The skill provides clear individual steps (install, configure, run) but lacks explicit validation checkpoints. There's no workflow for verifying the build output is correct, no error recovery guidance, and the migration workflow just says 'npx tsdown-migrate' without validation steps. For a build tool that could produce broken packages, validation steps (like running publint/attw checks) should be more prominently integrated into the workflow rather than just listed as options.

2 / 3

Progressive Disclosure

The skill references many external files (references/*.md) via well-organized tables, which is good progressive disclosure structure. However, the SKILL.md itself is very long with 13+ inline code examples that could be in a separate patterns/examples file. The main file tries to be both a quick reference and a comprehensive cookbook, making it a borderline monolithic document. The broken table formatting (the tsdown-migrate note interrupts the Core References table) also hurts organization.

2 / 3

Total

9

/

12

Passed

Description

100%

Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.

This is a strong skill description that clearly communicates what the skill does and when to use it. It includes specific concrete actions, natural trigger terms, and an explicit 'Use when' clause. The only minor weakness is the 'blazing-fast speed' marketing language, which adds no functional value for skill selection, but overall the description is well-crafted and distinctive.

DimensionReasoningScore

Specificity

Lists multiple specific concrete actions: 'Bundle TypeScript and JavaScript libraries', 'generating type declarations', 'bundling for multiple formats', 'migrating from tsup'. These are concrete, actionable capabilities.

3 / 3

Completeness

Clearly answers both what ('Bundle TypeScript and JavaScript libraries... generating type declarations, bundling for multiple formats') and when ('Use when building libraries, generating type declarations, bundling for multiple formats, or migrating from tsup') with an explicit 'Use when' clause.

3 / 3

Trigger Term Quality

Includes strong natural keywords users would say: 'TypeScript', 'JavaScript', 'libraries', 'type declarations', 'multiple formats', 'tsup', 'bundling'. These cover common variations of how users would describe this need. Minor deduction consideration for 'blazing-fast speed powered by Rolldown' being somewhat marketing-speak, but the trigger terms are otherwise excellent.

3 / 3

Distinctiveness Conflict Risk

Clearly distinct niche: Rolldown-powered bundling for libraries with specific triggers like 'tsup migration', 'type declarations', and 'multiple formats'. Unlikely to conflict with general build tools or other bundler skills due to the specific technology references.

3 / 3

Total

12

/

12

Passed

Validation

100%

Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.

Validation11 / 11 Passed

Validation for skill structure

No warnings or errors.

Repository
antfu/skills
Reviewed

Table of Contents

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