nushell-plugin-builder
Guide for creating Nushell plugins in Rust using nu_plugin and nu_protocol crates. Use when users want to build custom Nushell commands, extend Nushell with new functionality, create data transformations, or integrate external tools/APIs into Nushell. Covers project setup, command implementation, streaming data, custom values, and testing.
87
82%
Does it follow best practices?
Impact
95%
1.20xAverage score across 3 eval scenarios
Advisory
Suggest reviewing before use
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 a strong skill description that clearly defines a narrow, specific domain (Nushell plugin development in Rust), lists concrete capabilities, and includes an explicit 'Use when' clause with natural trigger terms. It covers both the 'what' and 'when' comprehensively while maintaining distinctiveness through its specific technology focus.
| Dimension | Reasoning | Score |
|---|---|---|
Specificity | Lists multiple specific concrete actions: creating Nushell plugins in Rust, project setup, command implementation, streaming data, custom values, and testing. These are concrete, actionable capabilities. | 3 / 3 |
Completeness | Clearly answers both 'what' (guide for creating Nushell plugins in Rust covering project setup, command implementation, streaming, custom values, testing) and 'when' (explicit 'Use when' clause with multiple trigger scenarios like building custom commands, extending Nushell, creating data transformations, integrating external tools). | 3 / 3 |
Trigger Term Quality | Includes strong natural keywords users would say: 'Nushell plugins', 'Rust', 'nu_plugin', 'nu_protocol', 'custom Nushell commands', 'extend Nushell', 'data transformations', 'integrate external tools/APIs'. Good coverage of both technical crate names and natural language terms. | 3 / 3 |
Distinctiveness Conflict Risk | Highly distinctive niche: Nushell plugin development specifically in Rust using specific crates (nu_plugin, nu_protocol). Very unlikely to conflict with other skills given the narrow domain. | 3 / 3 |
Total | 12 / 12 Passed |
Implementation
64%Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.
This is a solid, highly actionable skill with complete executable Rust code examples covering the full plugin development lifecycle. Its main weaknesses are moderate verbosity (some explanatory text Claude doesn't need), missing validation checkpoints in the workflow, and a somewhat long main file that could better leverage its referenced documents for advanced content.
Suggestions
Add validation checkpoints to the workflow: verify cargo build succeeds before plugin add, verify plugin registration with 'plugin list', and include error recovery steps if registration fails.
Move the 'Common Patterns', 'Advanced Features', and 'Engine Interaction' sections into the referenced files (examples.md, advanced-features.md) to keep SKILL.md as a concise overview.
Remove explanatory commentary Claude already knows (e.g., 'This shows users exactly where the error occurred', descriptions of what binary vs text serialization formats are).
| Dimension | Reasoning | Score |
|---|---|---|
Conciseness | Generally efficient with good code examples, but includes some unnecessary explanations Claude would know (e.g., explaining what MsgPackSerializer vs JsonSerializer are, explaining what plugins are in the overview, the 'This shows users exactly where the error occurred' comment). The serialization section and some inline commentary could be tightened. | 2 / 3 |
Actionability | Excellent executable code throughout — complete plugin structure, cargo commands, signature definitions, argument access patterns, error handling, testing setup, and common patterns are all copy-paste ready with real Rust code. | 3 / 3 |
Workflow Clarity | The Quick Start provides a clear 3-step sequence (create, implement, build/install), and the Development Workflow section shows iterative development steps. However, there are no validation checkpoints — no verification that the plugin compiled correctly, no check that 'plugin add' succeeded, and no error recovery guidance if registration fails. | 2 / 3 |
Progressive Disclosure | Good structure with references to four separate files (plugin-protocol.md, advanced-features.md, examples.md, testing-debugging.md) and a scaffold script, but since no bundle files are provided, we cannot verify these exist. The main file itself is quite long (~200 lines) with inline content (Common Patterns, Advanced Features, Engine Interaction) that could arguably live in the referenced files instead. | 2 / 3 |
Total | 9 / 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.
- Repository
- YPares/agent-skills
- Commit
84b1da5
- Reviewed
Table of Contents
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