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Claude Fable 5.1 is Anthropic’s advanced AI model for coding, knowledge work, research, and long-running agentic tasks. It is designed to improve on Claude Fable 5 with stronger performance across software engineering, scientific research, multidisciplinary reasoning, computer use, business workflows, and complex problem solving. The model can handle extended multi-step work, verify its own results, diagnose difficult software issues, and operate effectively across tool-heavy workflows. Anthropic also reduced cache-read pricing for Fable 5.1, lowering typical usage costs compared with Fable 5 and creating larger savings for highly agentic workloads. Fable 5.1 includes updated safeguards intended to reduce false positives while allowing more legitimate cybersecurity tasks such as vulnerability discovery for defensive purposes. The model is available through Claude products, the Claude API, Amazon Web Services, Google Cloud, and Microsoft Azure.

GPT-6.1 Sol is an OpenAI model designed to deliver near-GPT-6 Astra intelligence at substantially lower cost across coding, professional work, computer use, scientific research, and agentic workflows. It improves on GPT-6 Sol across complex tasks such as software engineering, document analysis, multi-step business automation, and computer interaction. On DeepSWE v1.1, GPT-6.1 Sol matches GPT-6 Astra at roughly one-fifth of the cost while exceeding GPT-6 Sol's best score by 6.4 percentage points at a lower reasoning effort. The model also improves computer use, outperforming GPT-6 Sol by seven percentage points on the OSWorld 2.0 offline set at maximum reasoning effort while costing less than half as much per task. GPT-6.1 Sol provides improved factuality and alignment, including greater transparency about limitations and stronger adherence to user instructions during agentic tasks. It is available through ChatGPT Work, Codex, and the OpenAI API.