Master REST and GraphQL API design principles to build intuitive, scalable, and maintainable APIs that delight developers. Use when designing new APIs, reviewing API specifications, or establishing API design standards.
60
51%
Does it follow best practices?
Impact
Pending
No eval scenarios have been run
Passed
No known issues
Optimize this skill with Tessl
npx tessl skill review --optimize ./.agent/skills/api-design-principles/SKILL.mdQuality
Discovery
67%Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.
The description has a solid structure with an explicit 'Use when' clause that clearly defines trigger scenarios. However, it relies on marketing-style language ('delight developers') rather than concrete capabilities, and could benefit from more specific trigger terms that users naturally use when discussing API design.
Suggestions
Replace vague qualifiers ('intuitive, scalable, maintainable', 'delight developers') with specific actions like 'define endpoints, structure responses, handle versioning, design error formats'
Add more natural trigger terms users would say: 'endpoints', 'routes', 'OpenAPI', 'Swagger', 'API documentation', 'request/response format', 'HTTP methods'
| Dimension | Reasoning | Score |
|---|---|---|
Specificity | Names the domain (REST and GraphQL API design) and mentions some actions (designing, reviewing, establishing standards), but uses vague qualifiers like 'intuitive, scalable, maintainable' and 'delight developers' which are abstract rather than concrete capabilities. | 2 / 3 |
Completeness | Clearly answers both what (API design principles for REST and GraphQL) and when (designing new APIs, reviewing specifications, establishing standards) with an explicit 'Use when' clause containing specific triggers. | 3 / 3 |
Trigger Term Quality | Includes relevant keywords like 'REST', 'GraphQL', 'API design', 'API specifications', but misses common variations users might say such as 'endpoints', 'routes', 'schema', 'OpenAPI', 'Swagger', or 'API documentation'. | 2 / 3 |
Distinctiveness Conflict Risk | Reasonably specific to API design but could overlap with general coding skills, backend development skills, or documentation skills. The REST/GraphQL focus helps but 'API specifications' is broad enough to potentially conflict. | 2 / 3 |
Total | 9 / 12 Passed |
Implementation
35%Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.
This skill functions primarily as a pointer to external documentation rather than providing actionable guidance itself. The instructions are too abstract to be useful without the referenced playbook, and the 'when to use' sections add bulk without value. The skill would benefit from including at least one concrete example or pattern inline.
Suggestions
Add at least one concrete REST and one GraphQL example showing a well-designed endpoint/query with explanation of why it follows good principles
Replace the abstract 4-step instructions with specific, actionable guidance (e.g., 'Use plural nouns for REST resources: /users not /user')
Remove or significantly condense the 'Use this skill when' and 'Do not use this skill when' sections - Claude can infer appropriate contexts
Include a quick-reference checklist of key design principles inline rather than deferring everything to the playbook
| Dimension | Reasoning | Score |
|---|---|---|
Conciseness | The skill is relatively brief but includes some unnecessary content like the verbose 'Use this skill when' and 'Do not use this skill when' sections that explain obvious contexts Claude could infer. The intro sentence restates the description. | 2 / 3 |
Actionability | The instructions are extremely vague ('Define consumers, use cases, and constraints', 'Choose API style') with no concrete examples, code snippets, or specific guidance. Everything actionable is deferred to an external file. | 1 / 3 |
Workflow Clarity | There is a numbered 4-step sequence, but steps are abstract and lack validation checkpoints. No feedback loops or concrete verification steps are provided for what could be error-prone design decisions. | 2 / 3 |
Progressive Disclosure | References to external resources exist and are one level deep, but the main skill body is essentially empty of useful content. The skill over-delegates to external files without providing a meaningful overview or quick-start guidance. | 2 / 3 |
Total | 7 / 12 Passed |
Validation
90%Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.
Validation — 10 / 11 Passed
Validation for skill structure
| Criteria | Description | Result |
|---|---|---|
frontmatter_unknown_keys | Unknown frontmatter key(s) found; consider removing or moving to metadata | Warning |
Total | 10 / 11 Passed | |
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