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Episode 1. Claude Opus 4.6 Review - The New Era of 1M Token Context
4.66min
ClaudeClaude Opus 4.61M Token ContextAI CodingDevelopment Tools
Claude Opus 4.6 is now available in beta. We'll explain the key new features like 1M token context window, 128k token output, and Adaptive Thinking in a way that's easy for junior developers to understand.
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Claude Opus 4.6 Announcement
Hello, fellow developers!
On February 5, 2026, Anthropic made an exciting announcement: Claude Opus 4.6 is now available in beta.
When I was a junior developer, I would have wondered "What's so different about this?" So today, I'll explain Opus 4.6's new features in an easy-to-understand way.
1M Token Context Window: "This is a Big Deal!"
First things first: Opus 4.6 supports the first Opus-level 1M token context window.
How Big is 1M Token?
Not sure what a token is? Let me explain simply:
- 1 Token ≈ 4 characters (English-based, Korean may vary)
- 1M Tokens ≈ 750,000 words or about 150-200 pages of a book
In practical terms, this means you can process the following tasks all at once:
- Large Codebase Analysis: Understand thousands of files at once
- Long Document Summarization: Process hundreds of pages of technical documents
- Complex Project Refactoring: Grasp the entire architecture and get suggestions in one go
Why Does This Matter for Junior Developers?
When you start coding, you often need to understand the full context even for small file modifications.
For example:
- Adding Features: You need to understand existing code to add new features
- Fixing Bugs: You need to see all related code to understand why a bug occurs
- Refactoring: You need to grasp the entire structure to improve code
With limited context, AI can lose track and give irrelevant answers. But with 1M tokens, these worries are greatly reduced.
128k Token Output: "Generate Long Code in One Go"
Another important feature is 128k token output.
What Problems Existed Before?
When AI generates code, there's a limit on output length. This caused frequent issues:
- Code would get cut off, requiring "continue" requests
- Had to generate in multiple files, which was inconvenient
- Sometimes resulted in inconsistent code
Benefits of 128k Token Output
128k tokens means you can generate over 10,000 lines of code at once. This is a huge advantage in practice:
- Complete File Generation: Create long files without interruption
- Consistent Code Style: The entire code has consistent style since it's generated at once
- Complex Module Implementation: Handle multiple interdependent files at once
Adaptive Thinking: "Thinking Smarter"
Opus 4.6 introduces a new feature called Adaptive Thinking. It adjusts the depth of thinking based on task complexity.
Effort Levels Explained
You can control thinking depth with the Effort parameter:
| Effort | Description | Suitable Tasks |
|---|---|---|
| low | Quick processing of simple tasks | Simple code edits, Q&A |
| medium | Normal thinking | General coding tasks |
| high | Deep thinking | Complex problem solving, architecture design |
| max | Maximum depth thinking | Hardest problems, creative work |
Tips for Junior Developers
At first, you might wonder "Which level should I use?" Based on my experience:
- I use medium by default: It's the right depth for most tasks
- Complex bugs or refactoring: I use high. Sometimes you need deeper thinking
- Simple questions or quick fixes: low is sufficient
Terminal-Bench 2.0 Top Scores
Anthropic announced that Opus 4.6 achieved top scores on Terminal-Bench 2.0.
What is Terminal-Bench?
Terminal-Bench measures how well AI performs terminal commands. It's a benchmark that shows real-world development performance.
Opus 4.6 improved over previous versions in:
- File System Operations: Better at manipulating files
- Debugging: Improved debugging performance
- Complex Command Sequences: Better at handling complex command sequences
Context Compaction (Beta)
This is still in beta. Context Compaction automatically compresses old conversation history, keeping only important information.
Why Do We Need This?
Long conversations can run out of tokens. By summarizing previous conversations, you can save tokens.
It's still in beta, so stability needs to be monitored, but it's an exciting feature to look forward to.
Pricing Policy
Standard Pricing
| Type | Input | Output |
|---|---|---|
| Opus 4.6 (under 200k) | $5 / million tokens | $25 / million tokens |
| Opus 4.6 (over 200k) | $10 / million tokens | $37.50 / million tokens |
Cost-Effective Usage Tips
From a junior developer's perspective, cost is an important consideration. Here are some tips:
- Use Opus only when needed: Cheaper models are sufficient for simple tasks
- Adjust Effort Level: Cost varies with thinking depth
- Manage Context: Remove unnecessary information when working
Safety Assessment
Anthropic also strengthened Opus 4.6's safety. Specifically:
- Harmful Content Blocking: Better at filtering dangerous code or content
- Bias Reduction: More balanced handling of diverse perspectives
Wrapping Up
Opus 4.6 has seen significant improvements. Especially the 1M token context is incredibly helpful for large-scale projects.
From a junior developer's perspective, I feel these tools accelerate learning speed. You can view entire codebases at once and learn faster.
In the next episode, we'll dive into the Agent Teams feature. It's a cool feature where multiple Claudes work together as a team!
We'll continue with Episode 2: Agent Teams Complete Guide.