Complete Claude Code Guide and Best Practices

You don't need to write code to ship a working app anymore. You need to describe what you want clearly enough that Claude Code builds it for you.

But "describe what you want" is deceptively simple. The result depends on how you structure the request, what rules you set upfront and how you break the build into steps.

This guide walks through the full process, from installation to a deployed project. We also cover Claude Code security and best practices.

Claude Code is a terminal-based coding agent from Anthropic. You give it an instruction like "add error handling to the payment module" and it figures out which files to read, plans the changes, edits the code and runs your tests to verify the result.

It runs on Claude's models. Claude Opus handles complex multi-file reasoning. Claude 3.5 and Claude 3 handle faster, lighter tasks. You can switch models mid-session with /model if you need to.

The difference from chatting with Claude in a browser is that Claude Code has direct access to your file system. It can create, edit and delete files, run shell commands and install packages.

P. S. Claude's latest version, Fable 5.2, is live on SYNTX.AI. It's built for the most demanding coding and agentic tasks.

You can download the native installer from Anthropic's site. It auto-updates and doesn't need Node.js. Open a new terminal, run claude, and if it launches, you're all set.

Then, navigate to your project folder and run claude there. It scans the project structure and builds a map of your codebase. From that point, you type instructions and Claude executes them.

If you're starting a new project, run /init. Claude scans the directory and generates a starter CLAUDE.md file with conventions it detected. You edit it from there.

Claude Code memory works through a file called CLAUDE.md in your project root. Claude reads it at the start of every session. Whatever rules you write here, Claude follows every time without you repeating them.

Without CLAUDE.md, Claude guesses your preferences. It might pick a different framework, ignore your naming conventions or skip your tests. With it, you encode those decisions once and stop correcting them session after session.

What to put in CLAUDE.md?

Your coding standards, framework choices, deploy commands, off-limits files and testing requirements. Here are examples by project type.

Next.js project:

• Use TypeScript strict mode, no any types
• Style with Tailwind, no CSS modules
• Test with Vitest, run with npm test
• Never edit files in legacy/
• Deploy with vercel --prod

Python API:

• Python 3.12, type hints on all functions
• Use repository pattern, no raw SQL in controllers
• Format with Black, lint with Ruff
• Test with pytest, run with make test
• Never commit .env files

WordPress site:

• PHP 8.2, follow WordPress coding standards
• Edit only the custom theme in wp-content/themes/my-theme/
• Never touch core files or other plugins
• Test locally with wp-env start

How long should CLAUDE.md be?

Under 200 lines. Every line loads on every turn and costs tokens, so keep that in mind if you want to cut costs. For each line, ask: "If I remove this, will Claude make mistakes?" If the answer is no, remove it. If the instruction is only needed sometimes, move it to a skill.

One trick: HTML comments (<!-- notes for humans -->) get stripped before hitting context. Notes to your future self cost zero tokens.

Slash commands are shortcuts you type instead of writing a full prompt. They're the fastest way to control a session.

Built-in commands you'll use most:

• /clear — wipes context and starts fresh. Use between unrelated tasks.
• /compact — summarizes the session to free context space.
• /model — switches the model mid-session (e.g., from Opus to Sonnet for a quick task).
• /cost — shows token usage and spend for the current session.
• /init — generates a starter CLAUDE.md by scanning the project.
• /review — triggers a code review (if you've set one up as a skill).
• /permissions — shows or adjusts what Claude can do without asking.
• /agents — lists available subagents.
• /help — lists every available command, built-in and custom.

Custom commands:

Create a markdown file at .claude/commands/my-command.md and invoke it with /my-command. Useful for team-specific actions like "run our deploy checklist" or "generate a changelog from recent commits."

The difference between a slash command and a skill is that slash commands are explicit, so you type the command and it runs. Skills are implicit, so Claude decides to load them based on context. Use commands for actions you trigger manually and Skills for knowledge Claude should pull in automatically.

Claude Code Skills are instruction packs that load only when relevant. A skill sits dormant until the current task matches its description, which keeps your Claude Code context window clean.

How Skills work

A skill is a folder with a SKILL.md file inside .claude/Skills/your-skill-name/. At startup, Claude reads just the name and one-line description of each skill (a few tokens). The full body loads only when triggered. You can install dozens of Skills without bloating context.

What to turn into a skill

Anything you do more than once a week and want done the same way every time:

• Code review against your team's specific standards
• Documentation in your project's format
• A debugging playbook that follows your triage steps
• A deploy checklist that verifies each step
• A PR template that formats descriptions consistently

Where to find Skills

The Claude Skills library has grown fast. Anthropic's official repo includes built-in Skills like /code-review, /verify and /run. Community packages cover broader workflows. Claude Code plugins bundle Skills, hooks and configuration into installable packages from Git repos.

Skills vs. commands vs. hooks vs. subagents

This is the decision that trips most people up. Here's the rule:

• CLAUDE.md: Always-on project rules. Loads every turn.
• Slash commands: Manual triggers for specific actions. You type it, it runs.
• Skills: Contextual knowledge that loads when relevant. Claude decides when.
• Hooks: Shell scripts that fire automatically at lifecycle events. No decision involved.
• Subagents: Separate Claude instances with their own context. For isolated, parallel work.

If a rule must be enforced every time, use a hook. If it's knowledge Claude should apply when relevant, use a skill. If it's an action you trigger yourself, use a command. If it would flood your context, delegate it to a subagent.

The Claude Code context window fills up as you work. Every file Claude reads, every change it makes, every error message stays in the window. Model accuracy drops as context grows. One benchmark showed models losing accuracy from 95% to 60% past a threshold.

Claude Code best practices for context

Use /compact before you hit the wall, not after. Add a compact policy to your CLAUDE.md that tells Claude what to preserve in the summary. Without it, /compact might drop decisions you need later.

Here's an example compact policy for CLAUDE.md.

When summarizing this conversation:

• Preserve all API changes and their rationale
• Keep error messages and their solutions
• Maintain the list of modified files
• Summarize exploration attempts briefly

Use /clear when you switch tasks. Old context from a previous task confuses the new one. Don't carry debugging context into a feature build.

If the same approach fails twice, /clear and rephrase. Failed attempts pollute context. Claude starts avoiding approaches that didn't work, even if the next attempt would have succeeded with a slight variation.

Delegate verbose tasks to subagents. Reading long documentation, comparing libraries, analyzing test output, basically, anything that generates a lot of text. The subagent works in its own context, returns the answer, and your main session stays clean.

Move detailed instructions out of CLAUDE.md. If a procedure is only needed sometimes, make it a skill. CLAUDE.md loads every turn. Skills load on demand.

Claude Code for vibe coding works because the agent creates files, installs packages, configures the project and runs it without your intervention. You describe the product, and Claude builds it.

Say you want to build a simple feedback form that saves responses to a database.

Step 1: Set the stack in CLAUDE.md

Use Next.js 15, Tailwind CSS, Prisma with SQLite.

Keep all API routes in app/api/.

Step 2: Prompt the first milestone

"Create a feedback form with fields for name, email and message. Style it with Tailwind. No backend yet, just the UI."

Claude creates the component, adds Tailwind classes, sets up the page route. You run npm run dev, check the result in your browser.

Step 3: Prompt the backend

"Add a Prisma schema for feedback submissions with the same three fields plus a timestamp. Create an API route that saves form submissions to the database."

Claude sets up Prisma, creates the schema, generates the migration, builds the API route and connects the form to it.

Step 4: Test

"Submit a test entry through the form and show me the database contents."

Claude runs the app, submits a test entry, queries the database and shows you the result.

Four prompts, working app. The key is breaking it into milestones rather than asking for everything at once.

When vibe coding breaks

Claude Code for vibe coding still produces code that needs checking. Common problems: the model picks a dependency you don't want, creates a file structure that doesn't match your conventions, or implements something that works but isn't secure. Review after every milestone. If you set up a code review skill, run it before moving on.

Claude is a solid choice for code review because it reads the surrounding codebase, not just the changed lines. It catches how changes interact with existing code, such as a function that breaks a downstream caller, a type change that propagates wrong, or an import that creates a circular dependency.

You can review ad hoc: "review the last three commits for security issues." Or build a code review skill that applies your team's standards every time: error handling, naming conventions, security headers, performance patterns. The review stays consistent regardless of who triggers it.

A practical skill setup is ti define what to check, what to ignore, and what format the output should take. "Flag issues as Critical, Warning or Note. Don't flag styling issues. Focus on security, error handling and logic errors." The skill runs the same way every time.

Claude Code workflows go beyond single prompts once you combine the primitives.

Hooks

Hooks are shell scripts that fire at lifecycle events. They don't rely on Claude remembering to do something but enforce it automatically. Practical Claude Code automation examples:

• PostToolUse: Run Prettier after every file edit, so formatting is always clean
• PreToolUse: Block writes outside the project directory
• Stop: run the test suite before Claude marks any task done
• Shell: Strip secrets from commands before they reach the model

Subagents

Subagents are separate Claude instances with their own context. Built-in types include Explore (read-only codebase exploration), Plan (planning without executing) and general-purpose.

You can also define custom subagents at .claude/agents/. A Claude Code review subagent runs in parallel, reviews the diff and returns findings without filling your main context with every line it checked.

MCP servers

MCP (Model Context Protocol) connects Claude Code to external tools like GitHub, Slack, databases, browsers and design tools. If a service has an MCP integration, Claude can interact with it directly from your session. Use /mcp to list, add or troubleshoot connections.

Is Claude Code safe? Yes, with the right configuration. Your code stays on your machine. Claude Code connects to Anthropic's API for inference, but your files don't leave your filesystem.

Claude Code security has four layers:

Permission modes control what Claude can do. You can restrict file writes to specific directories, block shell commands or require approval before any destructive action. Pre-approve safe operations (Git commands, read operations) in /permissions so you're not clicking "allow" on every turn, and reserve prompts for actions that actually matter.

Hooks enforce rules with code, not instructions. A PreToolUse hook blocks writes outside the project directory regardless of what Claude decides to do. A shell hook redacts secrets before they reach the model. Hooks run deterministically, and Claude can't override them.

Checkpoints let you roll back. Claude Code creates Git commits before changes, so you always have a revert path.

Sandboxing limits access. Claude only reaches what you give it access to.

Note: Don't paste API keys, passwords or tokens into prompts. Use environment variables and gitignored .env files. Claude Code respects .gitignore by default.

Claude Code vs Cursor is the most common comparison. They solve the same problem from opposite directions.

Cursor is an AI-powered code editor based on VS Code. It helps as you type, line by line, inside a file. You stay in control, and the AI suggests. It's the better pick for real-time editing where you want help with the current line.

Claude Code operates at project level. You describe a task and Claude reads the codebase, plans the approach and implements the changes across however many files it takes.

Many developers use both: Cursor for in-editor autocomplete and quick fixes and Claude Code for multi-file tasks, debugging and autonomous work. They complement each other rather than compete.

Grok Code vs Claude Code mainly comes down to ecosystem vs. cost.

Claude Code's advantage is the agent framework. Skills, hooks, subagents, CLAUDE.md, MCP and the plugin ecosystem give you a level of customization no other coding tool matches. Claude Opus 4.8 scores ~89% on SWE-bench Verified.

Grok's advantage is speed and cost per task. For straightforward coding that doesn't need agent infrastructure, Grok is competitive and cheaper to run.

Both Grok and Claude are available on SYNTX.AI, so you can test each on the same task.

Not using CLAUDE.md. Every session without it starts from zero. You spend the first five minutes re-explaining conventions Claude already forgot.

Prompting everything at once. "Build me a full CRM" produces a mess. "Create the contact list view with search and filter" produces something you can review.

Ignoring /cost. Long sessions burn tokens. Check spend periodically, especially when running subagents or processing large files.

Carrying context between unrelated tasks. Old debugging context pollutes a new feature build. Use /clear between tasks.

Skipping the review. Claude generates confident code that can still be wrong. Run tests. Check the diff. Use a code review skill. Don't trust the agent's words over actual evidence.

Claude Code is one of the best AI tools for coding so far, thanks to a terminal agent that reads your codebase, edits multiple files and verifies its changes by running tests. You can adjust it to your workflow with CLAUDE.md for project rules, skills for reusable instructions and hooks for automatic checks, and extend it with subagents and MCP connections to other tools.

It's available on SYNTX.AI alongside ChatGPT, DeepSeek, Gemini, Grok and 100+ other models for coding, writing, image generation, video production and more. Every user gets welcome tokens upon registration, so you can test the platform for free.

What is Claude Code?

A terminal-based coding agent from Anthropic. It reads your project, writes code across files, runs tests and executes shell commands from text instructions. Runs on Claude Opus, Claude 3.5 and Claude 3.

Is Claude Code free?

It requires an API key or subscription. For Claude AI free access, SYNTX.AI gives welcome tokens. This lets you test the model before you commit.

Is Claude Code safe?

Yes. It runs locally, your code stays on your machine, and permission modes control access. Hooks enforce security rules automatically. Keep credentials in environment variables, not prompts.

What are Claude Code Skills?

Instruction packs that load when a task matches their description. They teach Claude repeatable workflows without loading on every session. The Claude Skills library includes official and community Skills for code review, debugging, deployment and more.

What is CLAUDE.md?

A memory file in your project root that Claude reads every session. It contains your coding standards, framework choices and project rules. It's how Claude stops forgetting your preferences.

What are hooks in Claude Code?

Shell scripts that run automatically at lifecycle events, like after a file edit or before a session ends. They enforce rules (formatting, security, testing) without relying on Claude to remember.