zod
TypeScript-first schema validation and type inference. Use for validating API requests/responses, form data, env vars, configs, defining type-safe schemas with runtime validation, transforming data, generating JSON Schema for OpenAPI/AI, or encountering missing validation errors, type inference issues, validation error handling problems. Zero dependencies (2kb gzipped).
82
78%
Does it follow best practices?
Impact
88%
2.51xAverage score across 3 eval scenarios
Passed
No known issues
Optimize this skill with Tessl
npx tessl skill review --optimize ./plugins/zod/skills/zod/SKILL.mdQuality
Discovery
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 an excellent skill description that clearly identifies its domain (TypeScript schema validation, likely Zod), lists numerous concrete use cases, and includes explicit trigger guidance via the 'Use for...' clause. It covers both proactive scenarios (defining schemas, transforming data) and reactive problem-solving scenarios (validation errors, type inference issues), making it highly discoverable. The description is concise yet comprehensive, with strong natural trigger terms.
| Dimension | Reasoning | Score |
|---|---|---|
Specificity | Lists multiple specific concrete actions: validating API requests/responses, form data, env vars, configs, defining type-safe schemas with runtime validation, transforming data, generating JSON Schema for OpenAPI/AI. Very detailed and actionable. | 3 / 3 |
Completeness | Clearly answers both 'what' (TypeScript-first schema validation and type inference) and 'when' with an explicit 'Use for...' clause listing numerous trigger scenarios including both proactive use cases and reactive problem scenarios like 'missing validation errors' and 'type inference issues'. | 3 / 3 |
Trigger Term Quality | Excellent coverage of natural terms users would say: 'schema validation', 'type inference', 'API requests/responses', 'form data', 'env vars', 'configs', 'JSON Schema', 'OpenAPI', 'validation errors', 'type inference issues'. These are terms developers naturally use when needing this kind of tool (likely Zod). | 3 / 3 |
Distinctiveness Conflict Risk | Highly distinctive with a clear niche: TypeScript schema validation with runtime validation and type inference. The combination of 'TypeScript-first', 'schema validation', 'runtime validation', and 'JSON Schema' creates a very specific identity unlikely to conflict with other skills. | 3 / 3 |
Total | 12 / 12 Passed |
Implementation
57%Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.
The skill excels at actionability with concrete, executable code examples and has excellent progressive disclosure with well-organized references. However, it is far too verbose — it essentially duplicates API documentation that Claude already knows (primitive types, object methods, array methods), includes redundant content (installation listed incorrectly three times), and has unnecessary marketing-style content at the bottom. The extensive API surface listing could be reduced to just the Zod 4-specific additions and non-obvious patterns.
Suggestions
Remove or drastically reduce the Primitive Types, Complex Types, and Quick Reference sections — Claude already knows standard Zod APIs. Focus only on Zod 4-specific changes and non-obvious patterns.
Fix the installation section which lists 'bun add zod' three times instead of showing npm/pnpm/bun/yarn alternatives.
Remove the 'What's New in This Version' marketing section and 'Production Notes' metadata — this is changelog content, not actionable guidance.
Move the comprehensive API listings (string validators, number validators, object methods) into a reference file rather than inlining them, keeping only Zod 4-specific APIs in the main skill.
| Dimension | Reasoning | Score |
|---|---|---|
Conciseness | The skill is extremely verbose at ~500+ lines. It includes extensive API reference listings that Claude already knows (primitive types, object methods, array methods), explains basic concepts like what parsing does, has a redundant installation section (lists 'bun add zod' three times), includes a changelog/marketing section at the bottom ('What's New in This Version' with sparkle emojis), and duplicates information between the quick reference and the body sections. | 1 / 3 |
Actionability | The skill provides fully executable, copy-paste ready code examples throughout — environment variable validation, API request validation, form validation, coercion patterns, discriminated unions, and more. Every code block is concrete TypeScript that could be directly used. | 3 / 3 |
Workflow Clarity | The skill covers individual validation patterns well but lacks explicit multi-step workflows with validation checkpoints. The migration section mentions loading a reference but doesn't provide a clear sequenced workflow. The API request validation example shows a basic parse-then-respond pattern but there's no broader workflow guidance for integrating Zod into a project or handling schema evolution. | 2 / 3 |
Progressive Disclosure | The skill has excellent progressive disclosure with a clear overview in the main file and well-signaled one-level-deep references to separate files (migration-guide.md, error-handling.md, advanced-patterns.md, type-inference.md, ecosystem-integrations.md, troubleshooting.md). The 'When to Load References' section provides clear guidance on when to consult each reference file. | 3 / 3 |
Total | 9 / 12 Passed |
Validation
81%Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.
Validation — 9 / 11 Passed
Validation for skill structure
| Criteria | Description | Result |
|---|---|---|
skill_md_line_count | SKILL.md is long (803 lines); consider splitting into references/ and linking | Warning |
metadata_field | 'metadata' should map string keys to string values | Warning |
Total | 9 / 11 Passed | |
- Repository
- secondsky/claude-skills
- Commit
88da5ff
- Reviewed
Table of Contents
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