Claude-Code-Everything-You-Need-to-Know

Claude Code: Everything You Need to Know

From first prompt to agent teams — one guide.

A practical guide to Claude Code — from your first prompt to multi-agent automation, hooks, MCP, and team workflows. Built around clear mental models and real examples, not marketing.

npm install -g @anthropic-ai/claude-code

Who this is for: Developers using (or about to use) Claude Code. Beginners get a guided path; power users get depth on Skills, Hooks, MCP, and Agent Teams.

---

Choose your path

You are…	Start here	Time
New to Claude Code	Setup → Prompt Engineering → Your First Skill	~15 min
⚡ Already using it, want depth	Skills · Hooks · MCP	~30 min each
Building teams or automation	Dynamic Workflows · Agent Teams · BMAD	varies

---

When to use what

The five extension points in Claude Code, side by side:

Tool	Use when…	Skip if…	Lives in
Skills (slash commands)	You repeat the same prompt or workflow ≥3 times	One-off task	.claude/commands/*.md
Hooks	You want code to run automatically on tool use, session start, etc.	You only want manual triggers	.claude/settings.json
Subagents	A subtask is big enough to need its own isolated context	The task fits in your main session	.claude/agents/*.md
Workflows	The job needs more agents than one conversation can coordinate	A couple of subagents would do	.claude/workflows/*.js
MCP servers	You need Claude to use external tools (browsers, DBs, APIs)	All your data is in local files	Configured per project

These five compose. Most polished setups combine 2–3.

---

What's inside

Fundamentals — What is Claude Code? · Setup · Prompt Engineering

Workflow extensions — Slash Commands · Skills · Hooks

Multi-agent & integration — Subagents · Dynamic Workflows · Agent Teams · Automation surface · MCP

Productivity & frameworks — Effort levels · Fast Mode · Super Claude · BMAD Method

Reference — Slash Command Cheatsheet · Effort levels · Workflows · Agent Teams · Skills · FAQ · Updates & Deprecations · Further Reading

What is Claude Code?

Claude Code is Anthropic's official CLI for working with Claude from your terminal. You point it at a project; it reads the code, plans, edits files, runs commands, and commits — all from the prompt line.

Three things it does that a chat UI can't:

• Reads your actual repo — not pasted snippets. Claude sees your file tree, runs grep, follows imports, and grounds answers in real context.
• Edits in place and runs your tests — diff-aware edits, then pytest/vitest/go test on the spot to verify the change.
• Composes with the rest of your stack — slash commands, hooks, sub-agents, MCP servers, and your normal git/shell workflow.

If you've used Copilot or Cursor, think of Claude Code as their "agent in your terminal" peer — same idea, different surface, no editor lock-in.

claude          # start a session in the current repo
> explain what this codebase does
> fix the failing test in src/api.test.ts
> open a PR with the changes

---

The Claude 5 era: today's model lineup

Three launches landed in quick succession this summer: Claude Opus 4.8 (May 28, 2026) took over as the Opus-tier flagship, Claude Fable 5 and its restricted sibling Claude Mythos 5 (June 9, 2026) opened a new Mythos-class tier above Opus, and Claude Sonnet 5 (June 30, 2026) became Claude Code's default model. 1M-token context is now standard across current Opus, Sonnet, and Fable models — no beta flag, no long-context surcharge — with 128K max output.

Choosing a model — quick guide:

Model	Reach for it when…
Sonnet 5 (default)	Everyday coding — most tasks live here. Intro pricing $2/$10 per MTok through Aug 31, 2026 (then $3/$15)
Opus 4.8	Complex reasoning, large refactors, orchestrating agents — $5/$25, unchanged from 4.7
Fable 5	Genuinely hard problems — Mythos-class capability above Opus at $10/$50
Haiku 4.5	Fast, lightweight tasks — quick questions, doc updates ($1/$5, 200K context)

Opus 4.7 / 4.6 and Sonnet 4.6 are now legacy models (still available via API and /model); Opus 4.1 retires August 5, 2026. Mythos 5 is the same underlying model as Fable 5 with fewer safeguards — invitation-only for approved organizations via Project Glasswing.

→ Full specs, capabilities, and pricing in docs/reference/models.md

---

Claude Code Setup

⏱️ 5-minute setup. Get from zero to your first AI-assisted commit.

1. Install

npm install -g @anthropic-ai/claude-code

Requires Node.js 18+. For other install methods (Homebrew, curl, native binary), see the official install guide.

2. Authenticate

claude

On first run, Claude Code opens a browser to sign in with your Anthropic account (Pro, Max, or API key all work). After that, you can re-authenticate any time with /login (and sign out with /logout) inside a session, or claude auth login|status|logout from your shell.

3. Run your first prompt

From any project directory:

cd ~/your-project
claude

Once Claude Code is running, try one of these:

• explain what this codebase does — Claude reads your repo and summarizes.
• add a README section about installation — generates content based on your project.
• find and fix the failing test in src/api.test.ts — diagnoses and edits in place.

4. (Optional) Generate a CLAUDE.md

/init

Creates a project-level instruction file that Claude reads on every session — your project's "house rules." More on this in Prompt Engineering Deep Dive.

5. (Bonus) Steal this repo's setup

This repo's .claude/ directory is a working, runnable Claude Code project — one of each extension point, not screenshots of one. Every path below is something you can copy into your own project today:

Path	What you get	Copy it when…
.claude/commands/	7 slash skills — /pr, /review, /tdd, /test, /five, /ux, /todo	You want PR hygiene and review rigor without writing the prompts
.claude/skills/	An Agent Skill — /claude-md-review audits a CLAUDE.md for vagueness, dead paths, and bloat	You want a worked example of the frontmatter contract
.claude/agents/	5 subagents, plus 10 more role prompts in specialized-agents/	You want specialists without authoring role prompts — they double as Agent Teams teammates
.claude/workflows/	A dynamic workflow — /stale-docs-audit fans agents across your docs, then refutes its own findings	You want a real script to read before writing your own
.claude/hooks/	Python hooks — post_tool_use.py, notification.py, stop.py, subagent_stop.py	You want lifecycle automation (needs uv)
.claude/settings.json	Permissions + hook wiring	You're copying the hooks — swap the hardcoded uv path for $(which uv)

git clone --depth 1 https://github.com/wesammustafa/Claude-Code-Everything-You-Need-to-Know /tmp/cc-guide
cp -r /tmp/cc-guide/.claude/commands/pr.md  your-project/.claude/commands/   # take what you want

⚠️ Read before you copy. Skills, hooks, agents, and workflows are executable instructions that run with your permissions — including from this repo. Copy file by file and read each one, the same way you'd review a shell script before sourcing it. Don't cp -r a whole .claude/ you haven't opened.

Next: Claude Skills to build your own in 3 minutes.

---

Prompt Engineering Deep Dive

** Claude Initialization** Run the /init command to automatically generate a CLAUDE.md file. Your CLAUDE.md files become part of Claude's prompts, so they should be refined like any frequently used prompt. A common mistake is adding extensive content without iterating on its effectiveness. Take time to experiment and determine what produces the best instruction following from the model.

1. Explore → Plan → Code → Commit

Versatile workflow for complex problems.

• Explore: Read relevant files/images/URLs; use subagents for verification. Do not code yet.
• Plan: Ask Claude to make a plan. Use "think", "think hard", "think harder", or "ultrathink" to nudge depth in the prompt — see Effort levels for the full reasoning dial. Optionally save the plan for future reference.
• Code: Implement the solution; verify reasonableness as you go.
• Commit: Commit results, create pull requests, update READMEs/changelogs.

• Claude has two default modes: Plan Mode and Accept Edits Mode. You can toggle between them using the Shift + Tab keys.

** Pro Tip:** Research & planning first significantly improves performance for complex tasks.

---

2. Test-Driven Workflow (Write Tests → Code → Commit)

Ideal for changes verifiable with unit/integration tests.

• Write Tests: Create tests based on expected inputs/outputs; mark as TDD.
• Run & Fail Tests: Confirm they fail; no implementation yet.
• Commit Tests: Commit once satisfied.
• Write Code: Implement code to pass tests; iterate with verification via subagents.
• Commit Code: Final commit after all tests pass.

Clear targets (tests, mocks) improve iteration efficiency.

---

3. Visual Iteration (Code → Screenshot → Iterate → Commit)

• Provide screenshots or visual mocks.
• Implement code, take screenshots, iterate until outputs match mock.
• Commit once satisfied.

Iteration significantly improves output quality (2-3 rounds usually enough).

---

4. Effort levels — how hard Claude thinks

→ Full guide in docs/reference/effort-levels.md

Mental model: Effort is a behavioural dial, not a token budget — it shifts thinking depth, tool-call appetite, response length, and how persistently Claude pushes through multi-step work. Higher ≠ smarter; context quality often matters more.

The API knows 5 levels (low → max, default high); Claude Code adds a sixth:

Level	Reach for it when…
low	Fast interactive queries you're steering — file renames, simple greps
medium	Gener