Claude Sonnet 4.5 (latest)

Claude Sonnet 4.5 sits within Anthropic's Claude Sonnet family and is positioned as a workhorse model for everyday professional workloads, from writing and analysis to software engineering assistance. The model is multimodal on input, accepting text, images, and PDF documents, while producing text output, which makes it well suited for tasks that combine documents or screenshots with natural language instructions. Its support for tool calling, structured output, attachments, reasoning, and temperature control indicates an emphasis on agentic workflows where the model must follow schemas, invoke external functions, and chain steps reliably across a session.

Although Anthropic does not publish pre-training data or a detailed recipe for Claude Sonnet 4.5, the broader Sonnet line is known for balancing strong reasoning with approachable latency, and the 4.5 release continues that trajectory with a generous context window suitable for long documents, codebases, and multi-turn agent loops. In practice this version fits developers building coding assistants and tool-using agents, knowledge workers who need to reason over attached files, and teams that want a dependable generalist model rather than a frontier-priced specialist. Compared with earlier Sonnet generations, the 4.5 iteration leans further into sustained agentic behavior, making it a practical default for production assistants that must remain coherent across many steps.