Claude Prompt Engineering: The Complete Guide (2026)

Master Claude AI Prompt Engineering

The difference between mediocre and incredible Claude responses comes down to how you prompt it. This guide teaches you every technique.

The Fundamentals

Be Specific

Bad: “Write some code” Good: “Write a Python function that takes a list of emails and returns only valid ones using regex. Include type hints and docstring.”

Provide Context

Bad: “Fix this bug” Good: “I’m building a React 19 app with TypeScript. The useEffect hook in UserProfile.tsx causes an infinite re-render when the user state updates. Here’s the code: [code]“

Define Output Format

Bad: “Tell me about databases” Good: “Compare PostgreSQL vs MySQL for a SaaS application. Format as a markdown table with columns: Feature, PostgreSQL, MySQL, Winner.”

System Prompts

System prompts set Claude’s behavior for the entire conversation:

You are a senior TypeScript developer with 10 years of experience.
- Always use TypeScript strict mode
- Prefer functional programming patterns
- Include error handling in all examples
- Write tests for every function
- Use JSDoc comments

In Claude Code

Create a CLAUDE.md file (acts as a persistent system prompt):

# Project Context
- Framework: Next.js 15 + TypeScript
- Database: PostgreSQL with Drizzle ORM
- Always use server components unless interactivity is needed
- Write tests with Vitest

In the API

client.messages.create(
    model="claude-sonnet-4-20250514",
    system="You are a helpful coding assistant...",
    messages=[...]
)

XML Structured Prompts

Claude responds excellently to XML-structured prompts:

<task>
Analyze the following code for security vulnerabilities
</task>

<code>
[paste your code here]
</code>

<requirements>
- Check for SQL injection
- Check for XSS vulnerabilities
- Check for authentication bypasses
- Rate severity: low/medium/high/critical
</requirements>

<output_format>
For each vulnerability found:
1. Location (file and line)
2. Type
3. Severity
4. Fix recommendation
</output_format>

Chain of Thought

Ask Claude to think step by step:

Solve this problem step by step. Show your reasoning at each step before giving the final answer.

Problem: [your complex problem]

Extended Thinking

Claude’s Extended Thinking mode enables deep reasoning:

Think deeply about this architectural decision. Consider:
1. Performance implications
2. Scalability concerns  
3. Maintainability
4. Security considerations

Then recommend the best approach with justification.

Advanced Techniques

Few-Shot Prompting

Provide examples of desired output:

Convert natural language to SQL. Examples:

Input: "Show all users who signed up last month"
Output: SELECT * FROM users WHERE created_at >= DATE_TRUNC('month', NOW() - INTERVAL '1 month') AND created_at < DATE_TRUNC('month', NOW());

Input: "Count orders by status"
Output: SELECT status, COUNT(*) FROM orders GROUP BY status;

Input: "Find the top 5 customers by total spend"
Output:

Role Prompting

You are a code review bot. Review code like a strict but kind senior engineer.
For each issue, provide:
- Severity (nit/suggestion/important/critical)
- The problematic code
- Why it's an issue
- The recommended fix

Constraint Prompting

Write a REST API for user management.

Constraints:
- Use Express.js with TypeScript
- Maximum 100 lines of code
- Include input validation with Zod
- Handle all error cases
- No external database (use in-memory array)
- Follow REST conventions strictly

Claude Code-Specific Prompts

Feature Development

Implement a dark mode toggle for the settings page.
- Use CSS variables for theme colors
- Persist preference in localStorage
- Add smooth transition animation
- Update all components that use hardcoded colors
- Write tests for the toggle behavior

Debugging

The /api/users endpoint returns 500 when email contains a plus sign (like user+tag@email.com).
Error log: [paste error]
Find the root cause and fix it. Run the tests after fixing.

Refactoring

Refactor src/utils/api.ts:
- Convert callbacks to async/await
- Add proper TypeScript types (no 'any')
- Add error handling with custom error classes
- Split into separate files by domain
- Maintain backward compatibility
- Update all imports across the project

Prompt Templates Library

Code Generation

Write a [LANGUAGE] [TYPE] that [DESCRIPTION].
Requirements: [LIST]
Include: error handling, types, tests, documentation.

Analysis

Analyze [SUBJECT] from the perspective of [ROLE].
Consider: [FACTORS]
Format: [OUTPUT FORMAT]

Comparison

Compare [A] vs [B] for [USE CASE].
Evaluate on: [CRITERIA]
Recommend the best choice with reasoning.

Common Mistakes

1. Too vague — Always be specific
2. No context — Provide background information
3. No format — Specify how you want the output
4. Too much at once — Break complex tasks into steps
5. Not iterating — Refine prompts based on results

Related Articles

• Best Claude Prompts for Coding — Ready-to-use templates
• Claude Code Tips — Power user techniques
• CLAUDE.md Guide — Persistent prompt config
• What is Claude AI? — Overview