Skip to content

Java Agent Skills (Claude + Gemini)

Popular Java / Spring Boot skills that work in both Claude Code and Gemini CLI, and how to install them once for both.

Why one skill works in both

Both tools follow the Agent Skills open standard: a skill is a folder with a SKILL.md (YAML frontmatter + markdown instructions), plus optional reference files.

1
2
3
spring-data-jpa/
├── SKILL.md          # name + description (frontmatter) + instructions
└── references/       # optional, loaded only when needed

1
2
3
4
5
---
name: spring-data-jpa
description: Use when generating or refactoring JPA entities, repositories, queries...
---
# instructions for the agent ...

description is what the agent reads to decide when to load the skill. Only name + description sit in context until the skill is triggered.

Tool-specific frontmatter (e.g. allowed-tools for Claude Code) is ignored by the other tool, so the same folder is safe to share.

Where each tool looks

Claude Code Gemini CLI
User (all projects) ~/.claude/skills/<name>/SKILL.md ~/.gemini/skills/ or ~/.agents/skills/
Project .claude/skills/<name>/SKILL.md .gemini/skills/ or .agents/skills/
List skills /skills, or ask "what skills do you have?" /skills list, gemini skills list --all
Install from git copy folder, or /plugin marketplace add for plugin repos gemini skills install <url> --consent
Link a local dir symlink /skills link <path> --scope user
Activation auto, when description matches auto, after a consent prompt

Stars as of 2026-09.

Repo ★ Java skills Good for
anthropics/skills 178k none Java-specific reference for how to write skills
github/awesome-copilot 39k java-springboot, java-junit, java-docs, spring-boot-testing, javax-to-jakarta-migration, java-refactoring-extract-method, java-add-graalvm-native-image-support, create-spring-boot-java-project short, general best-practice skills
Jeffallan/claude-skills 11.6k java-architect, spring-boot-engineer, kotlin-specialist broad "senior engineer" persona skills
spring-ai-community/spring-ai-agent-utils 0.6k — (library) running skills inside your own Spring AI app
giuseppe-trisciuoglio/developer-kit 0.3k ~50 in plugins/developer-kit-java/: spring-boot-test-patterns, unit-test-* (service, controller, wiremock...), spring-data-jpa, spring-boot-resilience4j, spring-boot-saga-pattern, aws-sdk-java-v2-*, langchain4j-* deep testing + AWS + LangChain4j
jdubois/dr-jskill 0.3k dr-jskill (single skill) generating a new Spring Boot 4 / Java 25 project
rrezartprebreza/spring-boot-skills 0.3k 33 skills × spring-boot-3/ and spring-boot-4/: spring-data-jpa, transactional-patterns, webflux-reactive-patterns, testing-pyramid, resilience-retry, spring-security-jwt, multi-module-maven, hexagonal-architecture, spring-modulith... focused, version-specific Spring Boot skills
a-pavithraa/springboot-skills-marketplace <0.1k code-reviewer, creating-springboot-projects, spring-data-jpa, springboot-migration small, review + migration

Suggested starter set

Need Skill
General Spring Boot rrezartprebreza/.../spring-boot-3/* (pick the ones you use) or awesome-copilot/java-springboot
JPA without N+1 rrezartprebreza/.../spring-data-jpa
@Transactional pitfalls rrezartprebreza/.../transactional-patterns
WebFlux rrezartprebreza/.../webflux-reactive-patterns
Tests developer-kit/.../spring-boot-test-patterns + unit-test-service-layer
New project jdubois/dr-jskill

Fewer, focused skills

Every installed skill puts its description in context and competes for triggering. Pick 5–10 you actually need rather than installing a whole repo.

Install once, use in both

Keep one copy of each skill and symlink it into both tools.

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
# 1. clone sources once
mkdir -p ~/skills-src && cd ~/skills-src
git clone --depth 1 https://github.com/rrezartprebreza/spring-boot-skills
git clone --depth 1 https://github.com/giuseppe-trisciuoglio/developer-kit

# 2. pick skills into one shared folder
mkdir -p ~/.agents/skills
for s in spring-data-jpa transactional-patterns webflux-reactive-patterns testing-pyramid; do
  ln -s ~/skills-src/spring-boot-skills/skills/spring-boot-3/$s ~/.agents/skills/$s
done
ln -s ~/skills-src/developer-kit/plugins/developer-kit-java/skills/spring-boot-test-patterns \
      ~/.agents/skills/spring-boot-test-patterns

# 3. Gemini CLI reads ~/.agents/skills directly — nothing to do

# 4. Claude Code: link each skill into ~/.claude/skills
mkdir -p ~/.claude/skills
for s in ~/.agents/skills/*; do ln -s "$s" ~/.claude/skills/; done

Update later: git -C ~/skills-src/spring-boot-skills pull. Both tools see the change.

Verify:

1
2
gemini skills list --all      # Gemini
# Claude Code: /skills, or ask "what skills do you have?"

Per project instead of per user: same idea with .agents/skills/ and .claude/skills/ in the repo root, committed to git, so teammates on either tool get the same skills.

Writing your own portable skill

  • Only rely on name + description in frontmatter; everything else is optional.
  • Write the description as when to use, with keywords: "Use when writing JPA entities, repositories, @Query, pagination...".
  • Keep SKILL.md short; move long examples into references/*.md and link them.
  • Don't mention tool names (Read, Bash, /command) in the instructions: they differ between Claude and Gemini.
  • Test the trigger in both tools with a prompt that should and one that shouldn't load it.

This site's java-architect skill

Java Architect Skill uses the same frontmatter layout as Jeffallan/claude-skills/java-architect, customised for Agrona/Aeron services. To make it portable, place it at .agents/skills/java-architect/SKILL.md and symlink into .claude/skills/.

Sources