Claude Code: Part 2 - CLAUDE.md Configuration Files

The Problem

You've started using Claude Code, and it's incredibly capable. Too capable. It suggests complex architectural changes when you wanted a simple bug fix. It writes elaborate documentation when you needed a quick comment. It refactors your entire component when you asked it to fix one function.

Claude is like an enthusiastic new team member who doesn't yet understand your project's constraints, coding standards, or the difference between "quick fix" and "complete rewrite."

You need a way to teach Claude about your project's specific context, rules, and boundaries.

The Solution

CLAUDE.md files act as a persistent memory system and rule book for your project. Think of it as onboarding documentation that teaches Claude about your project's specific needs, just like you'd brief a new human developer.

How CLAUDE.md Works

Place a CLAUDE.md file in your project root with rules and context:

# Project: E-commerce Platform

## Tech Stack
- Next.js, TypeScript, Tailwind, Prisma

## Rules
- Use TypeScript strict mode
- Follow patterns in src/components/
- Functional components only

Claude now follows your project-specific rules automatically.

Memory Hierarchy

Claude Code respects a hierarchy of configuration files, with more specific files overriding general ones:

Configuration Hierarchy

1. Personal: ~/.claude/CLAUDE.md - Your preferences across all projects
2. Project: ./CLAUDE.md - Team rules for this project
3. Local: ./CLAUDE.local.md - Personal overrides (gitignored)
4. Folder: ./src/auth/CLAUDE.md - Module-specific rules

More specific files override general ones.

Multi-AI Tool Sharing

Want to use Claude Code alongside other AI tools? The CLAUDE.md approach works for now, but there's an initiative to create a universal standard called AGENT.md. Learn more at ampcode.com/AGENT.md.

For now, you can create a symlink to share the same configuration:

# Create shared memory file
mkdir ~/.ai-tools
touch ~/.ai-tools/shared-memory.md

# Link it as CLAUDE.md
ln -s ~/.ai-tools/shared-memory.md ./CLAUDE.md

# Link for other AI tools
ln -s ~/.ai-tools/shared-memory.md ./AI-CONTEXT.md
ln -s ~/.ai-tools/shared-memory.md ./CURSOR-RULES.md

Benefits:

• One source of truth for project context
• Consistent behavior across AI tools
• Easy maintenance and updates

Writing Effective Rules

Be specific and concise:

❌ "Use good coding practices"
✅ "Functional components, TypeScript, max 200 lines"

Set clear boundaries:

• Never modify payment code without review
• No new packages without approval
• No breaking API changes

Token Consumption Warning

⚠️ Keep CLAUDE.md files under 100 lines! They're included in every interaction.

Write concisely:

❌ "Always ensure components use hooks rather than classes"
✅ "Functional components only"

Best Practices

• Start with 5-10 essential rules
• Remove outdated rules regularly
• Test rules work: "Create a component following our patterns"
• Review monthly, prune verbosity

Getting Started

1. Create CLAUDE.md with 5-10 essential rules
2. Test it works
3. Keep it under 100 lines
4. Update monthly

CLAUDE.md transforms Claude into a project-aware teammate.

Claude Code Blog Series

Previous: Part 1 - Getting Started and Installation
Next: Part 3 - Conversation Management and Context

Full Series:

1. Part 1 - Getting Started and Installation
2. Part 2 - CLAUDE.md Configuration Files (this post)
3. Part 3 - Conversation Management and Context
4. Part 4 - Slash Commands and Custom Commands
5. Part 5 - MCP Servers and Tool Integration
6. Part 6 - Subagents and Task Delegation
7. Part 7 - IDE Integration with VS Code and JetBrains
8. Part 8 - Hooks for Automated Quality Checks
9. Part 9 - Complete Development Workflows
10. Part 10 - Power User CLI Options and Scripting
11. Part 11 - Troubleshooting and Recovery