mcollina/fastify-best-practices
Guides development of Fastify Node.js backend servers and REST APIs using TypeScript or JavaScript. Use when building, configuring, or debugging a Fastify application — including defining routes, implementing plugins, setting up JSON Schema validation, handling errors, optimising performance, managing authentication, configuring CORS and security headers, integrating databases, working with WebSockets, and deploying to production. Covers the full Fastify request lifecycle (hooks, serialization, logging with Pino) and TypeScript integration via strip types. Trigger terms: Fastify, Node.js server, REST API, API routes, backend framework, fastify.config, server.ts, app.ts.
95
95%
Does it follow best practices?
Impact
Pending
No eval scenarios have been run
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 thoroughly covers the Fastify ecosystem with specific, actionable capabilities. It provides clear 'what' and 'when' guidance with explicit trigger terms, and is distinctly scoped to Fastify rather than generic backend development. The description is comprehensive without being padded, using third person voice throughout.
| 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 extensive capability list) 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-specific triggers like 'server.ts', 'app.ts', 'fastify.config'. These are terms users would naturally use when seeking help with Fastify development. | 3 / 3 |
Distinctiveness Conflict Risk | Highly distinctive — clearly scoped to Fastify specifically, not generic Node.js or Express. The trigger terms include Fastify-specific identifiers like 'fastify.config' and framework-specific concepts like 'Pino logging' and 'strip types', making it unlikely to conflict with other backend framework skills. | 3 / 3 |
Total | 12 / 12 Passed |
Implementation
70%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 hub skill that excels at progressive disclosure and workflow clarity through its scenario-based reading paths and clean file references. Its main weaknesses are mild verbosity (the 'When to use' and 'Core Principles' sections add little value) and limited standalone actionability since nearly all concrete guidance is delegated to sub-files. The quick start example is a nice touch but the skill could be tighter.
Suggestions
Remove or significantly trim the 'When to use' section — this duplicates the skill description and wastes tokens on information Claude can infer from context.
Remove or replace the 'Core Principles' section with Fastify-specific gotchas or anti-patterns that Claude wouldn't already know (e.g., common encapsulation mistakes, schema compilation caching behavior).
| Dimension | Reasoning | Score |
|---|---|---|
Conciseness | The 'When to use' section is somewhat redundant given the skill description and could be trimmed. The 'Core Principles' section states things Claude already knows (async/await support, encapsulation concepts). The quick start and navigation sections are efficient, but overall there's room to tighten. | 2 / 3 |
Actionability | The quick start provides a single executable code example, which is good. However, the SKILL.md itself is mostly a table of contents pointing to other files — the actual actionable guidance lives in the referenced rule files. The core principles are abstract rather than instructive. | 2 / 3 |
Workflow Clarity | The 'Recommended Reading Order for Common Scenarios' section provides clear, well-sequenced paths for different use cases. For a hub/overview skill that delegates to sub-files, this is an effective way to guide multi-step learning workflows. No destructive or batch operations require validation checkpoints at this level. | 3 / 3 |
Progressive Disclosure | Excellent progressive disclosure structure: concise overview with a quick start, scenario-based reading paths, and clearly signaled one-level-deep references to 19 individual rule files. Navigation is easy and well-organized. | 3 / 3 |
Total | 10 / 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
Table of Contents