Chapter 4: Skills

Learn to maintain project documentation and use skills to streamline writing tasks.

• Reading time: 10 minutes
• Practical time: 30-45 minutes

Reading

Briefs

• What is a Skill
• Tools Comparison

Assets

Documentation skills for exercises:

• Download: 04-skills.tar.gz

⚠️ Important: Extract and overwrite the skills for your chosen tool (Claude Code or Copilot CLI). These assets contain tool-specific skills that should replace any existing configuration in your project.

Practical

Exercise 1: Documentation with Skills

Use the technical-writer skill from the Assets section to create good documentation.

Task:

/technical-writer Create an ARCHITECTURE.md in /docs/ documenting the project structure and general architecture of each sub-project, taking into account the framework best practices that were used. Explore each sub-project before creating the documentation.

What to observe:

• How editorial principles affect output
• Differences from baseline version
• Structure and scannability improvements

Exercise 2: Create your own architecture-expert skill

Build a custom "expert" skill that loads architectural knowledge on demand.

Task:

1. Use the skill-creator skill from the archive to create an expert skill named architecture-expert
2. Provide the ARCHITECTURE.md file you created as input
3. Review the generated skill and description — it should trigger on keywords like "project structure", "architecture", or related terms
4. Test the skill:
   • Delete ARCHITECTURE.md
   • Reload your agent harness tool
   • Ask a question about the project's architectural constraints

What to observe:

• How the skill creator automates building project-specific skills
• Context loading on demand—information appears only when relevant keywords are detected
• Practical use case: feeding architectural constraints to the agent without cluttering every conversation

Exercise 3: Create your own unit-test-writer skill

Build a custom "expert" skill that writes unit tests on demand. This skill will help you further to write tests after fixing the bug in the application (chapter 5) and implementing the small feature (chapter 6).

Task:

1. Use the skill-creator skill from the archive to create an expert skill named unit-test-writer
2. Provide information for the new skill like:
   • What input should it accept
   • What kind of technologies to use (ex: JUnit 5 unit tests for Spring Boot services using Mockito and AssertJ)
   • What steps to have (ex: list scenarios, write one test per scenario, add private helper)
3. Review the generated skill and description — it should trigger on keywords like "write unit tests", "generate testing", or related terms
4. Test the skill:
   • Open src/test/java/.../OrderService.java and check the implementation
   • Use the skill to generate a unit test for that service
   • Make sure you specified in the prompt what kind of tests you expect and how the tests should run

What to observe:

• How well the skill interprets OrderService and covers its key business logic paths
• Whether tests run successfully without modification on the first try
• The skill's ability to reduce testing boilerplate and maintain consistency across the codebase

Bonus: Review the changes and accept or modify suggestions based on project needs. This demonstrates how skills can maintain consistency in specialized documentation like AI agent configuration files.