sandi-metz-rules
This skill should be used when users request code review, refactoring, or code quality improvements for Ruby codebases. Apply Sandi Metz's four rules for writing maintainable object-oriented code - classes under 100 lines, methods under 5 lines, no more than 4 parameters, and controllers instantiate only one object. Use when users mention "Sandi Metz", "code quality", "refactoring", or when reviewing Ruby code for maintainability.
Install with Tessl CLI
npx tessl i github:Dicklesworthstone/pi_agent_rust --skill sandi-metz-rules89
Does it follow best practices?
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npx tessl skill review --optimize ./path/to/skillValidation for skill structure
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 a strong skill description that clearly defines its scope (Ruby code quality using Sandi Metz's principles), provides specific actionable criteria (the four rules with concrete numbers), and includes explicit trigger guidance. The description effectively balances technical specificity with natural language triggers that users would actually say.
| Dimension | Reasoning | Score |
|---|---|---|
Specificity | Lists multiple specific concrete actions: 'code review, refactoring, or code quality improvements' and explicitly details Sandi Metz's four rules (classes under 100 lines, methods under 5 lines, no more than 4 parameters, controllers instantiate only one object). | 3 / 3 |
Completeness | Clearly answers both what (code review, refactoring, applying Sandi Metz's four rules) AND when with explicit 'Use when' clause specifying trigger terms and contexts like 'reviewing Ruby code for maintainability'. | 3 / 3 |
Trigger Term Quality | Includes natural keywords users would say: 'Sandi Metz', 'code quality', 'refactoring', 'Ruby code', 'maintainability', 'code review'. These are terms developers naturally use when seeking this type of help. | 3 / 3 |
Distinctiveness Conflict Risk | Highly distinctive with clear niche: specifically Ruby codebases + Sandi Metz's rules. The combination of language (Ruby), methodology (Sandi Metz), and specific numeric rules creates a unique fingerprint unlikely to conflict with generic code review skills. | 3 / 3 |
Total | 12 / 12 Passed |
Implementation
72%Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.
This skill provides solid, actionable guidance for applying Sandi Metz's rules with good code examples and clear structure. The main weaknesses are some verbosity in explanatory sections and missing explicit validation/feedback loops in the refactoring workflow. The progressive disclosure is well-handled with appropriate references to external documentation.
Suggestions
Remove the 'When to Use This Skill' section entirely - this duplicates the skill description and Claude can infer appropriate usage from context
Add explicit validation checkpoints to the refactoring workflow, e.g., 'Run tests after each extraction to verify behavior is preserved' with specific commands
Trim the overview paragraph - 'These rules are heuristics that encourage good design practices, making code easier to understand, test, and maintain' explains what Claude already knows
| Dimension | Reasoning | Score |
|---|---|---|
Conciseness | The skill contains some unnecessary explanation (e.g., 'These rules are heuristics that encourage good design practices') and could be tightened. The 'When to Use This Skill' section largely duplicates information Claude could infer from context. | 2 / 3 |
Actionability | Provides concrete, executable guidance with specific code examples for counting rules, RuboCop configuration, and clear refactoring patterns. The code counting examples are copy-paste ready and unambiguous. | 3 / 3 |
Workflow Clarity | Steps are listed clearly with numbered workflows, but validation checkpoints are weak. The refactoring workflow mentions 'Verify that tests still pass' but lacks explicit validation steps or feedback loops for error recovery. | 2 / 3 |
Progressive Disclosure | Well-structured with clear overview, appropriately references external file (references/rules.md) for detailed content, and organizes content into logical sections. Navigation is straightforward with one-level-deep references. | 3 / 3 |
Total | 10 / 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.
Validation — 11 / 11 Passed
Validation for skill structure
No warnings or errors.
- Reviewed
Table of Contents
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