xAI has unveiled its latest model, Grok 4.1 Fast, alongside the new Agent Tools API. Grok 4.1 Fast boasts a 2 million token context window and is designed for practical applications such as customer support and research. It supports tool calls, code execution, and web browsing, having been trained with long-term reinforcement learning across various domains. The model is accessible via the xAI API, with pricing set at $0.2 per million token input and $0.5 per million token output. A free trial is available on the OpenRouter platform for two weeks.