Small vs Medium LLMs: Why Qwen3 1.7B & 4B Failed a Simple JSON Task (But 8B Didn’t)
Benchmarks 2026 The "Reasoning Ceiling": Why 8B is the Minimum Viable Scale for AI Agents As we transition into Future-Ready Architectures , the "Monolithic Chatbot" is dying. It is being replaced by Agentic Workflows —specialized, modular units that use "Skills" to interact with structured data. But there is a silent killer in these architectures: Instruction Collapse. In my latest experiment, I pitted the Qwen3 family (1.7B, 4B, and 8B) against a production-grade JSON routing task. The results prove that while "small" models are fast, they lack the cognitive budget for structured autonomy. The Core Discovery: Reasoning and JSON discipline do not scale linearly. The jump from 4B to 8B isn't just an improvement; it’s the difference between a system that works and one that silently self-destructs. 🧪 The Experiment: Wardrobe Query Routing The models were tasked with parsing natural language into a boolean fi...