Claude Opus 4.5 represents a significant advancement in AI, particularly for agents. After two weeks of use, the author argues it surpasses previous models, specifically in its ability to manage longer tasks and deliver real-world results. The release timing, just before Thanksgiving and during NeurIPS, may have delayed wider recognition of its importance. The author likens this moment to the release of GPT-4 for chat and Sonnet 3.5 for coding, suggesting that Opus 4.5 fundamentally changes how we can work with AI agents. The Claude Agent SDK complements Opus 4.5, providing a robust framework for creating effective agents. The author emphasizes that the quality of the agent’s harness is nearly as vital as the model itself. This SDK, combined with Opus 4.5, allows developers to unlock new economic value and encourages those skeptical about agents to reconsider their stance. The potential for Opus 4.5 to reshape professional workflows is underscored by impressive revenue growth for Anthropic, the company behind these tools, which has seen 10x revenue increases annually for the past three years. Practical suggestions for maximizing Opus 4.5 include trusting it with complex tasks and using voice input for efficiency. The author highlights improvements in image input capabilities and encourages integration with tools like Obsidian. A standout feature is the new plan mode, which enhances productivity for complex tasks. The article also notes that Opus 4.5 excels in coding, with Claude Code being the top AI tool for coding tasks. It mentions the effectiveness of speculative branching and pseudocode usage, suggesting these strategies lead to better outcomes in software development.