Command & Prompt Templates

Module 15.2: Command & Prompt Templates

Estimated time: ~30 minutes

Prerequisite: Module 15.1 (CLAUDE.md Templates)

Outcome: After this module, you will have a library of prompt templates for common tasks and know how to create reusable prompts.

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1. WHY — Why This Matters

You do the same tasks repeatedly — code review, test generation, documentation. Each time you write the prompt from scratch. Sometimes you forget important criteria. Results vary in quality.

Prompt templates are pre-written prompts for common tasks. Write once, reuse forever. Consistent quality, nothing forgotten.

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2. CONCEPT — Core Ideas

Prompt Template Structure

# Template: [Task Name]

## Purpose
[What this template does]

## Prompt
[The actual prompt with {{placeholders}}]

## Variables
- {{code}}: Code to analyze
- {{file}}: Target file path

## Usage
[How to invoke this template]

Template Categories

Category	Templates	Use Case
Review	Code review, PR review	Quality assurance
Generate	Tests, docs, types	Create new content
Refactor	Extract, rename, optimize	Improve existing
Debug	Error analysis, logging	Find/fix issues
Explain	Code walkthrough	Understanding

Template Variables

Common placeholders for flexibility:

{{code}}      — Code to analyze
{{file}}      — File path
{{language}}  — Programming language
{{error}}     — Error message
{{context}}   — Additional context
{{criteria}}  — Specific requirements

Template Storage

• CLAUDE.md — Project-specific templates
• Personal folder — Your reusable templates
• Team repository — Shared team templates

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3. DEMO — Step by Step

Template 1: Code Review

# Template: Code Review

## Prompt
Review the following code for:

1. **Correctness**: Logic errors, edge cases, bugs
2. **Security**: Vulnerabilities, injection risks, auth issues
3. **Performance**: Inefficiencies, N+1 queries, memory leaks
4. **Maintainability**: Readability, naming, complexity
5. **Standards**: Does it follow our CLAUDE.md conventions?

Code to review:
{{code}}

Format response as:
- 🔴 Critical (must fix)
- 🟠 Important (should fix)
- 🟡 Suggestion (nice to have)
- ✅ Good practices observed

## Usage
Paste code, then use this template for structured review.

Template 2: Test Generation

# Template: Generate Tests

## Prompt
Generate comprehensive tests for:
{{code}}

Requirements:
- Use {{testFramework}} (Jest/Pytest/etc.)
- Cover happy path and edge cases
- Include error scenarios
- Mock external dependencies
- Follow AAA pattern (Arrange, Act, Assert)

Generate tests for:
1. Normal operation
2. Edge cases (empty, null, boundary)
3. Error handling
4. Integration points

## Usage
Paste function/class code to generate complete test file.

Template 3: Documentation

# Template: Generate Documentation

## Prompt
Generate documentation for:
{{code}}

Include:
1. **Overview**: What does this code do?
2. **Parameters**: All inputs with types
3. **Returns**: Output with type
4. **Examples**: 2-3 usage examples
5. **Errors**: What can be thrown?

Format: JSDoc/docstring appropriate for {{language}}

## Usage
Paste code to generate complete documentation.

Template 4: Debug Helper

# Template: Debug Analysis

## Prompt
I'm getting this error:
{{error}}

In this code:
{{code}}

Analyze:
1. What's causing this error?
2. Why is it happening?
3. How to fix it (provide code)?
4. How to prevent similar issues?

## Usage
Paste error message + code for root cause analysis.

Using Templates

Step 1: Copy template prompt
Step 2: Replace {{placeholders}} with actual values
Step 3: Paste into Claude session
Step 4: Get consistent, structured output

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4. PRACTICE — Try It Yourself

Exercise 1: Use Existing Template

Goal: Experience template consistency.

Instructions:

1. Take the code review template above
2. Apply it to a recent piece of your code
3. Compare results vs your typical ad-hoc review prompt
4. Note the consistency differences

💡 Hint

Focus on whether the template catches things you usually forget (security? edge cases?).

✅ Solution

Template review typically finds:

• Security issues (template reminds to check)
• Edge cases (explicit in template)
• Standards violations (references CLAUDE.md)

Ad-hoc reviews often miss 1-2 categories entirely.

Exercise 2: Create Your Own Template

Goal: Build a template for your workflow.

Instructions:

1. Identify a task you do repeatedly with Claude
2. Write the prompt you typically use
3. Formalize into template structure (Purpose, Prompt, Variables, Usage)
4. Test the template twice

💡 Hint

Good candidates: API endpoint review, component creation, migration scripts.

✅ Solution

Example: API Endpoint Template

# Template: API Endpoint Review

## Prompt
Review this API endpoint for:
- Input validation
- Error responses (correct status codes)
- Authentication/authorization
- Rate limiting consideration
- Documentation accuracy

Code: {{code}}

Test on 2 endpoints, refine based on results.

Exercise 3: Template Library

Goal: Build your personal template collection.

Instructions:

1. Create 5 templates for your common tasks
2. Store in a dedicated folder or document
3. Document when to use each
4. Test each on a real task

💡 Hint

Start with: review, test, doc, refactor, explain. These cover 80% of needs.

✅ Solution

Template library structure:

~/prompt-templates/
├── code-review.md
├── test-generation.md
├── documentation.md
├── refactoring.md
├── explanation.md
└── README.md (index + usage guide)

Each template tested on real code before adding to library.

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5. CHEAT SHEET

Template Structure

# Template: [Name]
## Purpose: [What it does]
## Prompt: [Actual prompt with {{variables}}]
## Variables: [List placeholders]
## Usage: [How to invoke]

Essential Templates

Template	Purpose
/review	Code review with criteria
/test	Generate test file
/doc	Generate documentation
/refactor	Refactoring suggestions
/debug	Error analysis
/explain	Code walkthrough

Common Variables

{{code}}      — Code to analyze
{{file}}      — File path
{{language}}  — Programming language
{{error}}     — Error message
{{context}}   — Additional context

Storage Locations

• CLAUDE.md (project-specific)
• Personal templates folder
• Team shared repository

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6. PITFALLS — Common Mistakes

❌ Mistake	✅ Correct Approach
Templates too vague	Specific criteria and output format
Forgetting variables	Always include {{placeholders}}
One giant template	Focused templates per task
No output format	Define what good response looks like
Never updating	Improve templates based on results
Templates only in head	Write down and share
Ignoring project context	Templates should reference CLAUDE.md

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7. REAL CASE — Production Story

Scenario: Vietnamese fintech team did 20+ code reviews weekly. Quality varied — some developers checked security, others didn’t. Some found edge cases, others missed them.

Template Solution:

Created /review template with mandatory sections:

• Security (SQL injection, XSS, auth)
• Performance (queries, memory)
• Business logic (edge cases, validation)
• Standards (team conventions)
• Test coverage (what needs tests)

Implementation:

• Week 1: Created standard review template
• Week 2: All reviews must use template
• Week 3: PR checklist added: “Reviewed using template”

Results (2 months):

• Security findings: +200% (template reminded to check)
• Review consistency: 95% same criteria applied
• Review time: Unchanged
• Production bugs from reviewed code: -40%

Quote: “Templates didn’t make us robots. They made sure we never forgot the important stuff. Each reviewer still adds their expertise on top.”

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Next: Module 15.3: Claude Code Skills →