Claude Sonnet 4.5

Claude Sonnet 4.5 is positioned as the flagship model for production coding and complex agentic workflows. The release announcement makes a bold claim—that it is the best coding model available—and sources indicate benchmark results support this positioning, showing meaningful improvements over previous Claude releases. The model excels at computer use, maintaining consistent performance across extended autonomous sessions that can stretch beyond 30 hours, a substantial leap from the roughly seven-hour capability of its predecessor Opus 4. This longevity makes it particularly suited for development environments where sustained reasoning through complex problems is essential, such as building sophisticated agents, debugging intricate systems, or automating multi-step software tasks.

Anthropic released Sonnet 4.5 alongside significant tooling upgrades designed to extend the model's reach into everyday workflows. The same Agent SDK that powers Claude Code—featuring context editing, memory tools, and token-aware conversation handling—is now available as building blocks for developers. The model integrates directly into Claude's applications, enabling code execution, file creation, and document generation within conversational interfaces. For teams building autonomous agents or integrating AI into development pipelines, this combination of extended operational persistence and accessible developer tooling represents a practical step toward more capable, long-running AI-assisted workflows.