Introducing Claude Sonnet 4.5: The Best Coding Model for Complex Agents

We backed Anthropic early because we believed the best AI would come from an expert team focused on solving real problems. Today's Claude Sonnet 4.5 launch delivers. The performance numbers tell the story: 77.2% on SWE-bench Verified. 30+ hours of autonomous work capacity. But beyond the metrics, Claude is delivering real power for production environments with smarter reasoning, faster performance, and superior coding capabilities. Apple and Meta use Claude internally. Goldman Sachs deployed it for production work. Cursor, Devin, and GitHub Copilot all integrate it. The developer ecosystem is already singing the praises of Claude Sonnet 4.5: ✨ Michael Truell (Cursor CEO): "State-of-the-art coding performance on longer horizon tasks" ✨ Devin: "18% planning improvement, 12% higher eval scores—the biggest jump since Sonnet 3.6" ✨ Danny Wu (Canva AI Lead): "Impressive gains on our most complex, long-context tasks—from engineers in our codebase to in-product features and research" ✨ Jeff Wang (Windsurf): "A new generation of coding models" ✨ GitHub Copilot: "Significant improvements in multi-step reasoning and code comprehension" ✨ Every.to: "Finished a comprehensive code review in two minutes that GPT-5 Codex took 10 minutes to complete" The Anthropic team's refusal to compromise on quality is what sets them apart. Watching Dario Amodei and the team ship at this pace—while maintaining this level of excellence—has been truly impressive. The market has spoken clearly: today's builders prioritize performance over price. The best model wins. Congratulations to the entire Anthropic team on launching Claude Sonnet 4.5!

Anthropic has released Claude Sonnet 4.5, highlighting major gains in coding, reasoning, and agent workflows with new features like code execution, file creation, and a VS Code extension. While benchmarks and safety claims look strong, the real proof will come from how it performs in everyday, real-world use. https://lnkd.in/gf_tNdwh

Claude Sonnet 4.5 is here, Major improvement in coding, reasoning, and agent building, along with developer tools like the Agent SDK, VS Code integration, and enhanced context handling for building complex agents.

Introducing Claude Sonnet 4.5 – the best coding model in the world and the strongest model for building complex agents. Sonnet 4.5 leads on SWE-bench Verified and can maintain focus for more than 30 hours on complex, multi-step tasks. It represents a major leap forward in computer use and agentic coding. Beyond the capabilities, this is our most aligned model yet, with substantial improvements in how the model communicates and behaves. We're also releasing the Claude Agent SDK—the same infrastructure that powers Claude Code—so developers can build agents with the same foundation we use. Read our blog post to learn more: https://lnkd.in/eTwp_3fs

Introducing Claude Sonnet 4.5 – the best coding model in the world and the strongest model for building complex agents. Sonnet 4.5 leads on SWE-bench Verified and can maintain focus for more than 30 hours on complex, multi-step tasks. We're also releasing the Claude Agent SDK—the same infrastructure that powers Claude Code—so developers can build agents with the same foundation we use. Sonnet 4.5 is available now as a drop-in replacement for Sonnet 4 at the same price. Full details at https://lnkd.in/gh_X5WjV

🚀 Claude Sonnet 4.5 in Action 🚀 In my earlier post, I said the coding landscape is reset. Now I’ve started testing Sonnet 4.5 in real backend debugging — and so far, it feels like Anthropic’s promise is holding up. Here’s what I’m noticing: 1️⃣ Sharper root cause detection — It traced why my form submission logic was pulling service definitions instead of user form data. With Sonnet 4, this would’ve taken far longer. 2️⃣ Context awareness — Instead of vague suggestions, it followed the function flow, showed where formData got overwritten, and sketched a clean fix. 3️⃣ Time savings (early signs) — What usually eats 45–60 minutes of console digging dropped to ~10. Exactly the kind of efficiency gain I was hoping for. It’s still early, but Sonnet 4.5 is shaping up to be more than a code generator. It’s behaving like a production-grade coding partner. 👉 What kind of multi-step, backend-heavy problem would you test it on first? 💬

We’ve switched Amp’s primary model to Claude Sonnet 4.5, Anthropic’s latest release. In our testing, Sonnet 4.5 showed clear improvements for developers, including: • Reduced sycophancy. • Higher success rates for file edits. • Improved reasoning during complex tasks such as debugging. The switch is automatic. Simply update to the latest version of Amp’s VS Code extension or CLI to start using Claude Sonnet 4.5. Smarter and more reliable coding assistance is now live with #Amp

✨ Building agents with the Claude Agent SDK The Claude Agent SDK (formerly the Claude Code SDK) is a collection of tools that helps developers build powerful agents on top of Claude Code. https://lnkd.in/dWR863Cg

A new Claude Code feature that I really like: since the introduction of Sonnet 4.5 (at least that's when I noticed it), it exhibited **initiative** of sorts. As in, it goes beyond the described scope of work and tries to guess what's next, and, in 90% of the cases, it gets it right. Here is an example of an actual output after a conversation "compact" at the end a unit of work - no input from myself whatsoever: "... Looking at the previous conversation, the last completed task was refactoring ProjectPickerPopover to include the built-in popover functionality. The build was successful. Following the established pattern from the previous work, I'll now create a MilestonePickerPopover component to complete the picker components for all editable fields in TaskDetailView. ..."

Are you a C++ developer looking to bring the Visualization Toolkit (VTK) to web applications? Use Docker! Transforming a complex C++ library like VTK to compile with WebAssembly (WASM) is a tedious and time-consuming process. To make this easier, we’ve introduced the vtk-wasm-sdk Docker image, which provides pre-built VTK.wasm libraries for both WASM32 and WASM64 architectures. In our walkthrough, we show how to use the SDK with the VTK GeometryViewer example. In just a few steps—configure, build, and serve—you’ll have a VTK application running in your browser! Here's how 👉 https://ow.ly/1SAZ50X4rq6 #VTK #OpenSourceTools #CppDevelopment #VisualizationToolkit #WebAssembly