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
• Work with images
• Use extended thinking
• Set up project memory
• Set up Model Context Protocol (MCP)
• Use Claude as a unix-style utility
• Create custom slash commands

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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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Use extended thinking

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Leverage Claude’s extended thinking for complex tasks

When to use: When working on complex architectural decisions, challenging bugs, or planning multi-step implementations that require deep reasoning.

> I need to implement a new authentication system using OAuth2 for our API. Think deeply about the best approach for implementing this in our codebase.

> think about potential security vulnerabilities in this approach
> think harder about edge cases we should handle

Tips to get the most value out of extended thinking:

Extended thinking is most valuable for complex tasks such as:

• Planning complex architectural changes
• Debugging intricate issues
• Creating implementation plans for new features
• Understanding complex codebases
• Evaluating tradeoffs between different approaches

The way you prompt for thinking results in varying levels of thinking depth:

• “think” triggers basic extended thinking
• intensifying phrases such as “think more”, “think a lot”, “think harder”, or “think longer” triggers deeper thinking

For more extended thinking prompting tips, see Extended thinking tips.

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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 any of:
  • The folder you run Claude in: Automatically added to conversations you start in that folder
  • Child directories: Claude pulls these in on demand
  • ~/.claude/CLAUDE.md: User-specific preferences that you don’t want to check into source control

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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 specialized 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 to specify where the configuration is stored:
  • local (default): Available only to you in the current project (was called project in older versions)
  • project: Shared with everyone in the project via .mcp.json file
  • user: Available to you across all projects (was called global in older versions)
• Set environment variables with -e or --env flags (e.g., -e KEY=value)
• Configure MCP server startup timeout using the MCP_TIMEOUT environment variable (e.g., MCP_TIMEOUT=10000 claude sets a 10-second timeout)
• Check MCP server status any time using the /mcp command within Claude Code
• MCP follows a client-server architecture where Claude Code (the client) can connect to multiple specialized servers

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Understanding MCP server scopes

When to use: You want to understand how different MCP scopes work and how to share servers with your team.

# Add a local-scoped server (default)
claude mcp add my-private-server /path/to/server

# Explicitly specify local scope
claude mcp add my-private-server -s local /path/to/server

# Add a project-scoped server
claude mcp add shared-server -s project /path/to/server

{
  "mcpServers": {
    "shared-server": {
      "command": "/path/to/server",
      "args": [],
      "env": {}
    }
  }
}

# Add a user server
claude mcp add my-user-server -s user /path/to/server

Tips:

• Local-scoped servers take precedence over project-scoped and user-scoped servers with the same name
• Project-scoped servers (in .mcp.json) take precedence over user-scoped servers with the same name
• Before using project-scoped servers from .mcp.json, Claude Code will prompt you to approve them for security
• The .mcp.json file is intended to be checked into version control to share MCP servers with your team
• Project-scoped servers make it easy to ensure everyone on your team has access to the same MCP tools
• If you need to reset your choices for which project-scoped servers are enabled or disabled, use the claude mcp reset-project-choices command

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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

> 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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Add MCP servers from JSON configuration

When to use: You have a JSON configuration for a single MCP server that you want to add to Claude Code.

# Basic syntax
claude mcp add-json <name> '<json>'

# Example: Adding a stdio server with JSON configuration
claude mcp add-json weather-api '{"type":"stdio","command":"/path/to/weather-cli","args":["--api-key","abc123"],"env":{"CACHE_DIR":"/tmp"}}'

claude mcp get weather-api

Tips:

• Make sure the JSON is properly escaped in your shell
• The JSON must conform to the MCP server configuration schema
• You can use -s global to add the server to your global configuration instead of the project-specific one

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Import MCP servers from Claude Desktop

When to use: You have already configured MCP servers in Claude Desktop and want to use the same servers in Claude Code without manually reconfiguring them.

# Basic syntax
claude mcp add-from-claude-desktop

claude mcp list

Tips:

• This feature only works on macOS and Windows Subsystem for Linux (WSL)
• It reads the Claude Desktop configuration file from its standard location on those platforms
• Use the -s global flag to add servers to your global configuration
• Imported servers will have the same names as in Claude Desktop
• If servers with the same names already exist, they will get a numerical suffix (e.g., server_1)

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Use Claude Code as an MCP server

When to use: You want to use Claude Code itself as an MCP server that other applications can connect to, providing them with Claude’s tools and capabilities.

# Basic syntax
claude mcp serve

{
  "command": "claude",
  "args": ["mcp", "serve"],
  "env": {}
}

Tips:

• The server provides access to Claude’s tools like View, Edit, LS, etc.
• In Claude Desktop, try asking Claude to read files in a directory, make edits, and more.
• Note that this MCP server is simply exposing Claude Code’s tools to your MCP client, so your own client is responsible for implementing user confirmation for individual tool calls.

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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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Create custom slash commands

Claude Code supports custom slash commands that you can create to quickly execute specific prompts or tasks.

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Create project-specific commands

When to use: You want to create reusable slash commands for your project that all team members can use.

mkdir -p .claude/commands

echo "Analyze the performance of this code and suggest three specific optimizations:" > .claude/commands/optimize.md

claude
> /project:optimize

Tips:

• Command names are derived from the filename (e.g., optimize.md becomes /project:optimize)
• You can organize commands in subdirectories (e.g., .claude/commands/frontend/component.md becomes /project:frontend:component)
• Project commands are available to everyone who clones the repository
• The Markdown file content becomes the prompt sent to Claude when the command is invoked

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Add command arguments with $ARGUMENTS

When to use: You want to create flexible slash commands that can accept additional input from users.

echo "Find and fix issue #$ARGUMENTS. Follow these steps:
1. Understand the issue described in the ticket
2. Locate the relevant code in our codebase
3. Implement a solution that addresses the root cause
4. Add appropriate tests
5. Prepare a concise PR description" > .claude/commands/fix-issue.md

claude
> /project:fix-issue 123

Tips:

• The $ARGUMENTS placeholder is replaced with any text that follows the command
• You can position $ARGUMENTS anywhere in your command template
• Other useful applications: generating test cases for specific functions, creating documentation for components, reviewing code in particular files, or translating content to specified languages

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Create personal slash commands

When to use: You want to create personal slash commands that work across all your projects.

mkdir -p ~/.claude/commands

echo "Review this code for security vulnerabilities, focusing on:" > ~/.claude/commands/security-review.md

claude
> /user:security-review

Tips:

• Personal commands are prefixed with /user: instead of /project:
• Personal commands are only available to you and not shared with your team
• Personal commands work across all your projects
• You can use these for consistent workflows across different codebases

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Next steps