java-21

Java 21 language and runtime patterns for modern, safe code. Trigger: When writing Java 21 code using records, sealed types, or virtual threads.

Quality

72%

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tessl review fix ./community/java-21/SKILL.md

Quality

Content

75%Weight 40%Scale 1-5

Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.

The content is a tight, well-structured Java 21 reference with executable examples for each pattern and a clear task-to-pattern mapping. It is held back from full marks only by minor cross-section repetition, a stubbed I/O method, and the lack of any deeper reference material to point to.

Suggestions

Collapse the overlap between "When to Use", "Critical Patterns", and the Quick Reference table so each pattern is stated once and cross-referenced.

Make the virtual-thread example fully executable by replacing the `blockingFetch` stub with a real call (e.g. `HttpClient.send`) or an explicit "fill in blocking call" note.

If deeper material exists, add a one-level reference (e.g. a PATTERNS.md) for edge cases like pinning and structured concurrency to push progressive disclosure higher.

Dimension	Reasoning	Score
Conciseness	The body is lean with one-line pattern intros and clean code, assuming Claude's Java competence; mild redundancy across "When to Use", "Critical Patterns", and "Quick Reference" (which all restate the same three patterns) keeps it just below the leanest anchor.	4 / 5
Actionability	Provides copy-paste-ready, compiling examples for all three patterns (record validation, sealed switch, virtual-thread executor), with only a minor gap — `blockingFetch` is an unimplemented stub and no example shows actual I/O.	4 / 5
Workflow Clarity	Clear task-to-pattern mapping via the "When to Use" list and the Quick Reference table makes application unambiguous; no destructive or batch operations are present so validation checkpoints are not required, but it is a reference set rather than a sequenced workflow.	4 / 5
Progressive Disclosure	Well-organized into clearly labeled sections (When to Use, Critical Patterns, Code Examples, Anti-Patterns, Quick Reference, Resources) with external resource links plainly signaled; no bundle files exist to split, and the ~110-line single file is appropriately self-contained, just above the under-50-line simple-skill threshold.	4 / 5
	Total	16 / 20 Passed

Description

70%Weight 40%Scale 1-5

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 clearly identifies its Java 21 niche and includes an explicit Trigger clause with concrete feature keywords, answering both what and when. It is held back from the top tier by a somewhat abstract "what" statement that lacks concrete action verbs.

Suggestions

Replace the generic "patterns for modern, safe code" with concrete actions, e.g. "Write immutable DTOs with records, model closed hierarchies with sealed types, and scale blocking I/O with virtual threads."

Add a few natural synonyms/users' phrases to the trigger (e.g. "pattern matching for switch", "Project Loom") to broaden keyword coverage.

Dimension	Reasoning	Score
Specificity	Names the Java 21 domain and concrete features ("records, sealed types, or virtual threads"), but the "what" is a generic noun phrase ("language and runtime patterns for modern, safe code") with no concrete action verbs, so it sits above the minimal-anchor but below the multi-action anchor.	3 / 5
Completeness	It answers both what ("Java 21 language and runtime patterns") and when via an explicit "Trigger:" clause with concrete triggers, but the "what" is less specific than the anchor-5 example that pairs concrete actions with trigger phrases.	4 / 5
Trigger Term Quality	"When writing Java 21 code using records, sealed types, or virtual threads" supplies the natural terms a developer would say, with good but not exhaustive coverage (no synonyms like "pattern matching" or "Loom").	4 / 5
Distinctiveness Conflict Risk	"Java 21" plus records/sealed types/virtual threads carves a clear niche with distinct triggers, though minor overlap risk remains with a hypothetical general "java" skill.	4 / 5
	Total	15 / 20 Passed

Validation

100%

Warnings & errors only

Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.

Validation — 16 / 16 Passed

Validation for skill structure

No warnings or errors.

Repository: Gentleman-Programming/Gentleman-Skills
Path: community/java-21/SKILL.md
Commit: c8036a3

Reviewed: 5 days ago

Table of Contents

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