Grok 4.1 Fast vs. GLM-5 vs. Claude Sonnet 4.5

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.

Claude Sonnet 4.5 marks a significant milestone in Anthropic's development of artificial intelligence, designed to excel in intricate coding environments, multifaceted workflows, and demanding computational challenges while emphasizing safety and alignment. This model establishes new standards, showcasing exceptional performance on the SWE-bench Verified benchmark for software engineering and achieving remarkable results in the OSWorld benchmark for computer usage; it is particularly noteworthy for its ability to sustain focus for over 30 hours on complex, multi-step tasks. With advancements in tool management, memory, and context interpretation, Claude Sonnet 4.5 enhances its reasoning capabilities, allowing it to better understand diverse domains such as finance, law, and STEM, along with a nuanced comprehension of coding complexities. It features context editing and memory management tools that support extended conversations or collaborative efforts among multiple agents, while also facilitating code execution and file creation within Claude applications. Operating at AI Safety Level 3 (ASL-3), this model is equipped with classifiers designed to prevent interactions involving dangerous content, alongside safeguards against prompt injection, thereby enhancing overall security during use. Ultimately, Sonnet 4.5 represents a transformative advancement in intelligent automation, poised to redefine user interactions with AI technologies and broaden the horizons of what is achievable with artificial intelligence. This evolution not only streamlines complex task management but also fosters a more intuitive relationship between technology and its users.