Common Mistakes to Avoid with Claude Code

After watching many developers use Claude Code, these are the most common mistakes and how to avoid them.

Mistake 1: Vague Prompts

The mistake

Fix it
Make it better
Clean this up

Why it fails

Claude doesn’t know:

What “it” is
What “better” means to you
What “clean” looks like

The fix

Fix the null pointer error on line 45 of auth.ts
by adding a check before accessing user.email

Refactor handleSubmit to use async/await instead
of .then() chains

Remove unused imports and sort remaining imports
alphabetically in utils.ts

Mistake 2: Not Providing Context

The mistake

Update the API

Why it fails

Which API? Update how? What’s the current state?

The fix

Update the /api/users endpoint to:
1. Accept an optional 'status' query parameter
2. Filter results when status is provided
3. Return all users when status is omitted

Currently the endpoint is in src/api/users.ts

Mistake 3: One Giant Prompt

The mistake

Build a complete e-commerce site with user auth,
product catalog, shopping cart, checkout with
Stripe, order history, admin dashboard,
inventory management, email notifications,
and analytics.

Why it fails

Too much for one conversation. Claude will:

Miss details
Create inconsistencies
Overwhelm the context window

The fix

Break it down:

Session 1: Set up user authentication
Session 2: Build product catalog
Session 3: Implement shopping cart
...

Mistake 4: Ignoring CLAUDE.md

The mistake

Not creating a CLAUDE.md, then being frustrated when Claude:

Uses wrong frameworks
Ignores coding conventions
Doesn’t know project structure

The fix

Create CLAUDE.md with:

Tech stack
Commands
Code style
Key files

Claude reads this automatically and follows it.

Mistake 5: Never Starting Fresh

The mistake

Using the same session for hours:

Context bloats
Old info persists
Responses slow down
Quality degrades

The fix

Start new sessions for new tasks. Use /compact during long sessions.

Mistake 6: Blindly Accepting Output

The mistake

Claude generates code → Immediately commit → Production breaks

Why it fails

Claude can:

Hallucinate APIs
Miss edge cases
Introduce subtle bugs

The fix

Claude generates code → Review → Test → Then commit

Mistake 7: Fighting the Tool

The mistake

Getting angry when Claude misunderstands:

I TOLD YOU THREE TIMES to use semicolons!!!

The fix

Check your CLAUDE.md for style rules
Provide clear examples
Start fresh if stuck
Report actual bugs to Anthropic

Claude isn’t being stubborn. It literally doesn’t remember.

Mistake 8: Using Wrong Model for Task

The mistake

Using Opus for every simple question:

/model opus
What's the port number in config?

Costs 60x more for no benefit.

The fix

Match model to task:

Haiku: Simple questions, searches
Sonnet: Most coding tasks
Opus: Complex reasoning only

Mistake 9: Not Using Available Features

The mistake

Manually doing what Claude automates:

Formatting code by hand (use hooks)
Creating boilerplate (use skills)
Running tests manually (use hooks)

The fix

Set up:

Hooks for auto-formatting and tests
Skills for repetitive workflows
Custom commands for common tasks

Mistake 10: Expecting Perfect Code

The mistake

Write the authentication system. It should be perfect.

Why it fails

First drafts are never perfect. Even human experts iterate.

The fix

Plan for iteration:

1. Generate initial implementation
2. Review and identify issues
3. Refine with specific feedback
4. Test and fix edge cases
5. Polish and finalize

Mistake 11: Skipping the Plan

The mistake

Diving into complex changes without planning:

Refactor the entire codebase to microservices

The fix

Use plan mode:

/plan
Let's think through the microservices refactoring...

Get alignment before making changes.

Mistake 12: Ignoring Error Messages

The mistake

Claude: Error: Cannot find module 'xyz'
You: Just fix it
Claude: Error: Cannot find module 'xyz'
You: FIX IT

The fix

Read the error. Provide context:

Getting "Cannot find module 'xyz'".
I installed it with npm install xyz.
The import is: import { thing } from 'xyz'
What's wrong?

Quick Reference

Mistake	Fix
Vague prompts	Be specific with files, lines, expectations
No context	Describe current state and desired state
Giant prompts	Break into multiple sessions
No CLAUDE.md	Create one with tech stack and conventions
Never fresh	Start new sessions for new tasks
Blind trust	Review and test before committing
Fighting	Clear prompts, fresh sessions
Wrong model	Match model to task complexity
Missing features	Use hooks, skills, commands
Expecting perfect	Plan for iteration

The Meta-Mistake

The biggest mistake: treating Claude as either:

A magic solution that should work perfectly
A dumb tool that can’t do anything

Reality: Claude is a capable assistant that needs clear direction and reasonable expectations. Work with it, not against it.