Introducing Grok 4.1 Fast and the xAI Agent Tools API. Grok 4.1 Fast is our best-performing tool invocation model to date. With a 2 million context window, it excels in real-world applications such as customer support and deep research. Grok 4.1 Fast combines cutting-edge tool invocation performance, ultra-fast inference, and high cost-effectiveness. We specifically built Grok 4.1 Fast for enterprise-level real-world applications. It is trained in various simulated environments across dozens of domains, achieving state-of-the-art performance in real-world intelligent workflows such as customer support. We train Grok 4.1 Fast using Long Temporal Reinforcement Learning (RL), focusing on multi-turn scenarios to ensure consistently stable performance across a full context window of 2 million tokens. We are also launching the Agent Tools API. With just a few lines of code, developers can enable Grok to autonomously browse the web, search for X posts, execute code, retrieve uploaded documents, and more. Grok 4.1 Fast excels in real-time information retrieval and deep research. Combining native X integration, code execution, and advanced web browsing capabilities, Grok 4.1 Fast + Agent Tools API tops the intelligent search benchmarks. All xAI Agent Tools will be available for free for the next two weeks. During this period, Grok 4.1 Fast will also be available for free, exclusively for OpenRouter users. The model has been officially released on the xAI API, priced at $0.20 per million tokens (input) and $0.50 per million tokens (output). Share your work and feedback with us on X. We can't wait to see your masterpieces!