Best Practices for Claude Code

The one constraint that shapes everything

Claude's context window holds your entire conversation — every message, every file it read, every command output. It fills up fast. A single debugging session can consume tens of thousands of tokens, and performance degrades as it fills. Claude may start overlooking earlier instructions or making more mistakes.

Almost every best practice in this lesson flows from this one constraint: manage context carefully, keep prompts focused, and reset often.

1. Always give Claude a way to verify its work

Without verification criteria, Claude produces something that looks right but may not work. You become the only feedback loop, and every mistake needs your attention.

2. Explore first, then plan, then code

Letting Claude jump straight to coding risks solving the wrong problem. Use plan mode to separate research from implementation.

3. Write specific prompts

The more precise your instructions, the fewer corrections you need. Claude can infer intent but it can't read your mind. Reference files, mention constraints, and point to examples.

You can also provide rich input: use @filename to reference files directly, paste screenshots by copying and dropping into the prompt, pipe data with cat error.log | claude, or paste a URL for Claude to fetch documentation.

4. Write an effective CLAUDE.md

CLAUDE.md is loaded at the start of every session. Include bash commands, code style rules, and workflow conventions that differ from sensible defaults. Run /init to generate a starter file from your current project.

# Code style
- Use ES modules (import/export), not CommonJS (require)
- Destructure imports when possible

# Workflow
- Always typecheck after a series of code changes
- Run single tests, not the full suite, for speed

# Repo etiquette
- Branch names: feat/<ticket>  fix/<ticket>
- PR titles must reference a ticket number

For each line ask: "Would removing this cause Claude to make a mistake?" If not, cut it. A bloated CLAUDE.md causes Claude to miss important rules buried in the noise.

5. Manage context aggressively

Long sessions accumulate irrelevant file contents, failed attempts, and detours. This degrades performance. A few commands keep the context clean:

6. Use subagents for investigation

When Claude needs to explore a lot of files to answer a question, those reads consume your context. Subagents run in a separate context window, explore, and then report back a summary — leaving your main conversation clean.

You can also use subagents for verification after implementation: use a subagent to review this code for edge cases. A fresh context means no bias toward code it just wrote.

7. Run parallel sessions to multiply output

Claude Code scales horizontally. Once you're comfortable with one session, run multiple in parallel for faster delivery or independent review.

A useful pattern is Writer / Reviewer: one session implements, another reviews with fresh context. Claude won't be biased toward code it wrote.

8. Automate with non-interactive mode

Use claude -p "prompt" in CI pipelines, pre-commit hooks, or scripts to run Claude without a session. The --output-format flag controls how output is structured for programmatic use.

# One-off query
claude -p "Explain what this project does"

# Structured output for scripts
claude -p "List all API endpoints" --output-format json

# Batch file migration
for file in $(cat files.txt); do
  claude -p "Migrate $file from React to Vue. Return OK or FAIL." \
    --allowedTools "Edit,Bash(git commit *)"
done

# Run autonomously with safety checks
claude --permission-mode auto -p "fix all lint errors"

9. Configure permissions to reduce interruptions

By default Claude asks before every file write or command. After the tenth click-through you stop reviewing. Three tools reduce this:

10. Avoid common failure patterns

Quick Reference