simon/fastify-best-practices
Fastify best practices skill
93
97%
Does it follow best practices?
Impact
85%
1.37xAverage score across 4 eval scenarios
Passed
No known issues
Quality
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 comprehensively covers what the skill does, when to use it, and includes rich trigger terms. It is highly specific to Fastify, listing concrete actions across the full development lifecycle, and clearly distinguishes itself from generic Node.js or other framework skills. The explicit 'Use when' clause and dedicated trigger terms section make it easy for Claude to select appropriately.
| Dimension | Reasoning | Score |
|---|---|---|
Specificity | Lists numerous specific concrete actions: defining routes, implementing plugins, JSON Schema validation, handling errors, optimising performance, managing authentication, configuring CORS and security headers, integrating databases, working with WebSockets, deploying to production, and more. | 3 / 3 |
Completeness | Clearly answers both 'what' (guides development of Fastify backend servers with a comprehensive list of capabilities) and 'when' (explicit 'Use when building, configuring, or debugging a Fastify application' clause plus explicit trigger terms section). | 3 / 3 |
Trigger Term Quality | Excellent coverage of natural terms users would say: 'Fastify', 'Node.js server', 'REST API', 'API routes', 'backend framework', plus file-level triggers like 'server.ts', 'app.ts', 'fastify.config'. Also includes domain terms like 'plugins', 'CORS', 'WebSockets', 'Pino' throughout the description. | 3 / 3 |
Distinctiveness Conflict Risk | Highly distinctive — clearly scoped to Fastify specifically, not generic Node.js or Express. The trigger terms and detailed Fastify-specific features (Pino logging, strip types, Fastify request lifecycle) make it very unlikely to conflict with other backend or API skills. | 3 / 3 |
Total | 12 / 12 Passed |
Implementation
87%Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.
This is a well-structured Fastify skill with excellent conciseness and actionability. The quick start provides three essential, copy-paste-ready patterns (server, plugin, typed route) without unnecessary explanation. The progressive disclosure is strong with scenario-based reading paths and a comprehensive file index. The main weakness is the lack of validation/verification guidance in the workflow, though this is partially mitigated by the skill being more of a reference hub than a step-by-step process.
Suggestions
Consider adding a brief verification step after the quick start server example (e.g., 'Test: `curl localhost:3000/health` → `{"status":"ok"}`') to establish a validation pattern.
| Dimension | Reasoning | Score |
|---|---|---|
Conciseness | The content is lean and efficient. The quick start examples are minimal but complete, covering the three most important patterns (server setup, plugin, typed route). No unnecessary explanations of what Fastify is or how Node.js works. Every section earns its place. | 3 / 3 |
Actionability | All three code examples are fully executable TypeScript with proper imports, type annotations, and realistic patterns. The TypeBox schema example is particularly well-done, showing the complete pattern including Static type inference and response schema. | 3 / 3 |
Workflow Clarity | The 'Recommended Reading Order' section provides useful scenario-based sequences, but there are no validation checkpoints or feedback loops. For a framework skill covering server setup and deployment, some guidance on verifying each step (e.g., testing the health endpoint, validating schema errors) would strengthen the workflow. | 2 / 3 |
Progressive Disclosure | Excellent progressive disclosure structure: concise quick-start overview with three key patterns, scenario-based reading paths for different use cases, and a comprehensive one-level-deep reference list to 19 detailed rule files with clear topic labels. | 3 / 3 |
Total | 11 / 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 |
|---|---|---|
metadata_version | 'metadata.version' is missing | Warning |
Total | 10 / 11 Passed | |
Reviewed
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