Claude 4: A Guide to the New AI Models - When and How to Use Them Effectively
Anthropic today unveiled the long-awaited Claude Opus 4 and Claude Sonnet 4 models, marking a fundamental shift in AI assistant capabilities. Let's explore what each model does best, pricing considerations, and when to choose which one.
Hybrid Models: Two Modes in One
The biggest innovation is the hybrid architecture of both models. Opus 4 and Sonnet 4 are hybrid models offering two modes: near-instant responses and extended thinking for deeper reasoning. In practice, this means:
Instant response mode: For quick queries, chat, simple tasks
Extended thinking mode: For complex analysis, planning, debugging
Additionally, they can actively use tools while thinking - searching the web, analyzing documents, or executing code, dramatically improving output quality.
Claude Opus 4: When You Need the Absolute Best
What It Can Do
Claude Opus 4 is the world's best coding model, leading on SWE-bench (72.5%) and Terminal-bench (43.2%). Its core strengths include:
Endurance: Anthropic announced that Claude Opus 4 can work autonomously for nearly a full workday - seven hours
Memory: When given access to local files, it creates notes and summarizes results, maintaining context throughout
Complexity: Handles thousands of steps in a single workflow
Real-World Examples
Yusuke Kaji from Rakuten Group Inc. reported: "When our team deployed Opus 4 on a complex open-source project, it coded autonomously for nearly seven hours - a huge leap in AI capabilities that left the team amazed."
Mike Krieger, Anthropic's CPO, shares his personal experience: "Prior to Opus 4 and Sonnet 4, I was mostly using the models as a thinking partner, but still doing most of the writing myself. They've crossed this threshold where now most of my writing is actually... Opus mostly."
Pricing and Availability
Cost: $15 per million input tokens, $75 per million output tokens
Savings: Up to 90% with prompt caching
Availability: Paid plans only (Pro, Max, Team, Enterprise)
Claude Sonnet 4: The Optimal Choice for Most Use Cases
Key Advantages
Claude Sonnet 4 is a significant upgrade to Claude Sonnet 3.7, delivering superior coding and reasoning while responding more precisely to your instructions. Key features:
Speed: Instant responses for interactive use
Precision: 80% reduction in "reward hacking" - the tendency to take shortcuts
Performance: 72.7% on SWE-bench - nearly matching Opus 4
Where It Excels
Customer support: Fast, accurate responses at low cost
Daily coding: Code review, debugging, minor updates
Interactive applications: Chatbots, real-time assistants
Content generation: Documentation, articles, reports
Pricing and Availability
Cost: $3 per million input tokens, $15 per million output tokens
Savings: 50% discount with batch processing
Availability: Available on free tier
Practical Guide: Which Model to Use When
Choose Opus 4 when you need:
Autonomous work for several hours
Complex refactoring of large codebases
Absolute accuracy without compromises
Budget for premium solutions
Critical business applications
Choose Sonnet 4 when you need:
Optimal price/performance ratio
Real-time responses
Regular development tasks
Customer-facing applications
Scalable solutions
New Integration Capabilities
Both models bring revolutionary possibilities:
Parallel tool use: Running multiple operations simultaneously
Web search during thinking: Active information retrieval for better answers
Enhanced memory: Storing key information for long-running tasks
Computer use: Controlling computers like a human (cursor movement, clicking, typing)
ROI Calculations: When Models Pay for Themselves
Opus 4 pays off when:
Replacing senior developer on specific tasks (7h work = ~$350-500 saved)
Reducing time-to-market for critical features
Decreasing production bugs
Sonnet 4 is cost-effective when:
Automating customer support (thousands of queries daily)
Accelerating code review processes
Generating technical documentation
Conclusion: The Future of AI Agents Is Here
Claude 4 models represent a crucial milestone - from AI helpers to true AI partners. Alex Albert from Anthropic noted that with previous models, you could achieve maybe 30 minutes to an hour of coherent performance, while Opus 4 works continuously for hours.
For businesses, this means the ability to delegate entire projects. For developers, it's a partner that truly understands code. And for all users, it's access to AI that can think, plan, and act almost like a human.
Recommendation: Start with Sonnet 4 for regular tasks and upgrade to Opus 4 for critical projects. Thanks to the hybrid architecture, you can leverage the best of both worlds - speed when you need it, depth when it matters.