Grok 4.1 Fast vs. GLM-5

Grok 4.1 Fast is xAI’s state-of-the-art tool-calling model built to meet the needs of modern enterprise agents that require long-context reasoning, fast inference, and reliable real-world performance. It supports an expansive 2-million-token context, allowing it to maintain coherence during extended conversations, research tasks, or multi-step workflows without losing accuracy. xAI trained the model using real-world simulated environments and broad tool exposure, resulting in extremely strong benchmark performance across telecom, customer support, and autonomy-driven evaluations. When integrated with the Agent Tools API, Grok can combine web search, X search, document retrieval, and code execution to produce final answers grounded in real-time data. The model automatically determines when to call tools, how to plan tasks, and which steps to execute, making it capable of acting as a fully autonomous agent. Its tool-calling precision has been validated through multiple independent evaluations, including the Berkeley Function Calling v4 benchmark. Long-horizon reinforcement learning allows it to maintain performance even across millions of tokens, which is a major improvement over previous generations. These strengths make Grok 4.1 Fast especially valuable for enterprises that rely on automation, knowledge retrieval, or multi-step reasoning. Its low operational cost and strong factual correctness give developers a practical way to deploy high-performance agents at scale. With robust documentation, free introductory access, and native integration with the X ecosystem, Grok 4.1 Fast enables a new class of powerful AI-driven applications.

GLM-5 is Z.ai’s most advanced open-source model to date, purpose-built for complex systems engineering, long-horizon planning, and autonomous agent workflows. Building on the foundation of GLM-4.5, it dramatically scales both total parameters and pre-training data while increasing active parameter efficiency. The integration of DeepSeek Sparse Attention allows GLM-5 to maintain strong long-context reasoning capabilities while reducing deployment costs. To improve post-training performance, Z.ai developed slime, an asynchronous reinforcement learning infrastructure that significantly boosts training throughput and iteration speed. As a result, GLM-5 achieves top-tier performance among open-source models across reasoning, coding, and general agent benchmarks. It demonstrates exceptional strength in long-term operational simulations, including leading results on Vending Bench 2, where it manages a year-long simulated business with strong financial outcomes. In coding evaluations such as SWE-bench and Terminal-Bench 2.0, GLM-5 delivers competitive results that narrow the gap with proprietary frontier systems. The model is fully open-sourced under the MIT License and available through Hugging Face, ModelScope, and Z.ai’s developer platforms. Developers can deploy GLM-5 locally using inference frameworks like vLLM and SGLang, including support for non-NVIDIA hardware through optimization and quantization techniques. Through Z.ai, users can access both Chat Mode for fast interactions and Agent Mode for tool-augmented, multi-step task execution. GLM-5 also enables structured document generation, producing ready-to-use .docx, .pdf, and .xlsx files for business and academic workflows. With compatibility across coding agents and cross-application automation frameworks, GLM-5 moves foundation models from conversational assistants toward full-scale work engines.