Claude Code tutorials

This guide provides step-by-step tutorials for common workflows with Claude Code. Each tutorial includes clear instructions, example commands, and best practices to help you get the most from Claude Code.

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Table of contents

• Understand new codebases
• Fix bugs efficiently
• Refactor code
• Work with tests
• Create pull requests
• Handle documentation
• Use advanced git workflows
• Work with images
• Set up project memory
• Use Claude as a unix-style utility
• Set up Model Context Protocol (MCP)

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Understand new codebases

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Get a quick codebase overview

When to use: You’ve just joined a new project and need to understand its structure quickly.

$ cd /path/to/project

$ claude

> give me an overview of this codebase

> explain the main architecture patterns used here
> what are the key data models?
> how is authentication handled?

Tips:

• Start with broad questions, then narrow down to specific areas
• Ask about coding conventions and patterns used in the project
• Request a glossary of project-specific terms

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Find relevant code

When to use: You need to locate code related to a specific feature or functionality.

> find the files that handle user authentication

> how do these authentication files work together?

> trace the login process from front-end to database

Tips:

• Be specific about what you’re looking for
• Use domain language from the project

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Fix bugs efficiently

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Diagnose error messages

When to use: You’ve encountered an error message and need to find and fix its source.

> I'm seeing an error when I run npm test

> suggest a few ways to fix the @ts-ignore in user.ts

> update user.ts to add the null check you suggested

Tips:

• Tell Claude the command to reproduce the issue and get a stack trace
• Mention any steps to reproduce the error
• Let Claude know if the error is intermittent or consistent

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Refactor code

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Modernize legacy code

When to use: You need to update old code to use modern patterns and practices.

> find deprecated API usage in our codebase

> suggest how to refactor utils.js to use modern JavaScript features

> refactor utils.js to use ES2024 features while maintaining the same behavior

> run tests for the refactored code

Tips:

• Ask Claude to explain the benefits of the modern approach
• Request that changes maintain backward compatibility when needed
• Do refactoring in small, testable increments

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Work with tests

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Add test coverage

When to use: You need to add tests for uncovered code.

> find functions in NotificationsService.swift that are not covered by tests

> add tests for the notification service

> add test cases for edge conditions in the notification service

> run the new tests and fix any failures

Tips:

• Ask for tests that cover edge cases and error conditions
• Request both unit and integration tests when appropriate
• Have Claude explain the testing strategy

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Create pull requests

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Generate comprehensive PRs

When to use: You need to create a well-documented pull request for your changes.

> summarize the changes I've made to the authentication module

> create a pr

> enhance the PR description with more context about the security improvements

> add information about how these changes were tested

Tips:

• Ask Claude directly to make a PR for you
• Review Claude’s generated PR before submitting
• Ask Claude to highlight potential risks or considerations

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Handle documentation

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Generate code documentation

When to use: You need to add or update documentation for your code.

> find functions without proper JSDoc comments in the auth module

> add JSDoc comments to the undocumented functions in auth.js

> improve the generated documentation with more context and examples

> check if the documentation follows our project standards

Tips:

• Specify the documentation style you want (JSDoc, docstrings, etc.)
• Ask for examples in the documentation
• Request documentation for public APIs, interfaces, and complex logic

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Work with images

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Analyze images and screenshots

When to use: You need to work with images in your codebase or get Claude’s help analyzing image content.

# 1. Drag and drop an image into the Claude Code window

# 2. Copy an image and paste it into the CLI with ctrl+v

# 3. Provide an image path
$ claude
> Analyze this image: /path/to/your/image.png

> What does this image show?
> Describe the UI elements in this screenshot
> Are there any problematic elements in this diagram?

> Here's a screenshot of the error. What's causing it?
> This is our current database schema. How should we modify it for the new feature?

> Generate CSS to match this design mockup
> What HTML structure would recreate this component?

Tips:

• Use images when text descriptions would be unclear or cumbersome
• Include screenshots of errors, UI designs, or diagrams for better context
• You can work with multiple images in a conversation
• Image analysis works with diagrams, screenshots, mockups, and more

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Set up project memory

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Create an effective CLAUDE.md file

When to use: You want to set up a CLAUDE.md file to store important project information, conventions, and frequently used commands.

> /init

Tips:

• Include frequently used commands (build, test, lint) to avoid repeated searches
• Document code style preferences and naming conventions
• Add important architectural patterns specific to your project
• You can add CLAUDE.md files to the folder you run Claude in, parent directories (Claude reads these automatically), or child directories (Claude pulls these in on demand)

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Use Claude as a unix-style utility

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Add Claude to your verification process

When to use: You want to use Claude Code as a linter or code reviewer.

Steps:

// package.json
{
    ...
    "scripts": {
        ...
        "lint:claude": "claude -p 'you are a linter. please look at the changes vs. main and report any issues related to typos. report the filename and line number on one line, and a description of the issue on the second line. do not return any other text.'"
    }
}

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Pipe in, pipe out

When to use: You want to pipe data into Claude, and get back data in a structured format.

$ cat build-error.txt | claude -p 'concisely explain the root cause of this build error' > output.txt

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Set up Model Context Protocol (MCP)

Model Context Protocol (MCP) is an open protocol that enables LLMs to access external tools and data sources. For more details, see the MCP documentation.

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Configure MCP servers

When to use: You want to enhance Claude’s capabilities by connecting it to specialied tools and external servers using the Model Context Protocol.

# Basic syntax
$ claude mcp add <name> <command> [args...]

# Example: Adding a local server
$ claude mcp add my-server -e API_KEY=123 -- /path/to/server arg1 arg2

# List all configured servers
$ claude mcp list

# Get details for a specific server
$ claude mcp get my-server

# Remove a server
$ claude mcp remove my-server

Tips:

• Use the -s or --scope flag with project (default) or global to specify where the configuration is stored
• Set environment variables with -e or --env flags (e.g., -e KEY=value)
• MCP follows a client-server architecture where Claude Code (the client) can connect to multiple specialized servers

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Connect to a Postgres MCP server

When to use: You want to give Claude read-only access to a PostgreSQL database for querying and schema inspection.

$ claude mcp add postgres-server /path/to/postgres-mcp-server --connection-string "postgresql://user:pass@localhost:5432/mydb"

# In your Claude session, you can ask about your database
$ claude
> describe the schema of our users table
> what are the most recent orders in the system?
> show me the relationship between customers and invoices

Tips:

• The Postgres MCP server provides read-only access for safety
• Claude can help you explore database structure and run analytical queries
• You can use this to quickly understand database schemas in unfamiliar projects
• Make sure your connection string uses appropriate credentials with minimum required permissions

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Next steps