Claude Opus 4.5 & Claude Code Setup: Complete Guide 2025

What You'll Learn

This guide covers everything you need to get started with the newly released Claude Opus 4.5:

• Understanding the new "Effort Parameter" and "Thinking Blocks"
• Installing the Claude Code CLI and VS Code Extension
• Configuring your API keys and environment
• Using Computer Use features with the new Zoom capability
• Optimizing costs with the new pricing model

📋 System Requirements

Minimum Requirements for Claude Code

🚀 Step 1: Install Claude Code

Anthropic has released "Claude Code," an agentic coding tool that lives in your terminal or VS Code. It is the primary way to interact with Opus 4.5 for development.

Option A: Install via Terminal (Recommended)

curl -fsSL https://claude.ai/install.sh | bash

brew install --cask claude-code

irm https://claude.ai/install.ps1 | iex

Option B: VS Code Extension (Beta)

1. Open VS Code Extensions (Ctrl+Shift+X)
2. Search for "Claude Code" by Anthropic
3. Click Install
4. Reload VS Code to activate the sidebar panel

🔐 Step 2: Authentication & Configuration

Before using Opus 4.5, you must authenticate the CLI with your Anthropic account.

1. Open your terminal
2. Run the login command:

   claude login

3. A browser window will open. Log in to your Anthropic Console account.
4. Authorize the CLI application.
5. Once successful, you can set Opus 4.5 as your default model:

   claude config set model claude-opus-4-5-20251101

🎨 Step 3: Using the New "Effort Parameter"

One of the groundbreaking features of Claude Opus 4.5 is the Effort Parameter. This allows you to control how much "thinking" the model does before responding.

🎯 Step 4: Your First Opus 4.5 Project

Method 1: Autonomous Coding in Terminal

1. Navigate to your project folder: cd my-project
2. Start Claude Code:

   claude

3. Ask for a complex task using natural language:
   "Analyze the entire src folder and refactor the authentication flow to use JWTs. Please think deeply about edge cases before writing code."
4. Watch the Thinking Blocks: Opus 4.5 will preserve its reasoning context. You can see it planning, checking files, and self-correcting.
5. Approve Changes: Claude will present a diff. Press Enter to apply or R to reject/refine.

Method 2: Computer Use with Zoom

Opus 4.5 has enhanced "Computer Use" capabilities. It can now inspect your screen with pixel-perfect precision using the new Zoom Tool.

1. Enable computer use in settings: /config capabilities.computer_use true
2. Prompt: "Look at the browser window and tell me why the CSS alignment is off on the navbar."
3. Claude will take screenshots, zoom in on the specific element, and suggest the CSS fix.

⚙️ Essential Settings & Optimization

Recommended Config for Opus 4.5

💡 Why Upgrade to Opus 4.5?

1. 80.9% on SWE-bench Verified

Opus 4.5 is currently the #1 model on the SWE-bench leaderboard, solving real-world GitHub issues with higher accuracy than any competitor.

2. Thinking Block Preservation

Unlike previous models that "forgot" their internal reasoning between turns, Opus 4.5 keeps its "thought process" in context. This is crucial for multi-step debugging.

3. Cost Efficiency

At $5/million input tokens, it is cheaper than the original Claude 3 Opus, making high-intelligence agentic workflows affordable for daily use.

🔧 Troubleshooting Common Issues

Issue: "Rate Limit Exceeded"

Solution: Opus 4.5 is in high demand. If you hit limits on the Free tier, consider upgrading to a Pro workspace or using the API with a prepaid balance.

Issue: CLI Permission Denied

Solution: Run `claude doctor` to check permissions. On macOS/Linux, ensure you have read/write access to the project folder. Do NOT run as sudo if possible to avoid file ownership issues.

🎓 Next Steps

Now that you have Claude Opus 4.5 running, try these advanced workflows:

• Build a fully autonomous agent with Claude Agent SDK
• Compare Opus 4.5 vs Sonnet 4.5 for coding tasks
• Learn about Programmatic Tool Calling

❓ FAQ

Is Claude Opus 4.5 free?

Opus 4.5 is a premium model. It is available to Pro/Team subscribers on Claude.ai and via the API (paid per token). Claude Code CLI requires API credits.

Can Opus 4.5 really fix bugs autonomously?

Yes. With its high SWE-bench score and "High Effort" mode, it can navigate multiple files, reproduce bugs (if a test environment is provided), and implement fixes with high reliability.

Does it work with VS Code?

Yes, the new "Claude Code" extension for VS Code brings the power of Opus 4.5 directly into your editor sidebar.