posttrainllm/qwen3-4b-rest-fused

TEXT GENERATIONPricing:Input $0.4 / Cached $0.08 / Output $0.8Concurrent Unit Cost:1Model Size:4BQuant:BF16Context Size:32kTool Calling:SupportedPublished:Jul 3, 2026License:apache-2.0Architecture:Transformer0.0K Open Weights Featherless Exclusive Cold

The posttrainllm/qwen3-4b-rest-fused model is a 4 billion parameter Qwen3-4B variant developed by posttrainllm, specifically optimized for file-operation depth in tool-calling scenarios. This research specialist package, trained with a teacher-free ReST iteration method, demonstrates improved performance in file-system interactions and reduced side effects. It is designed for Mac-local tool-calling research or as a component behind an explicit agentic router, rather than general-purpose planning.

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Qwen3-4B ReST Fused: A Specialized Tool-Calling Model

This model, posttrainllm/qwen3-4b-rest-fused, is a 4 billion parameter variant of Qwen/Qwen3-4B-Instruct-2507, developed by posttrainllm. It was produced through a teacher-free ReST (Reinforcement Learning from Self-Training) loop, focusing on enhancing specific tool-calling capabilities.

Key Capabilities and Differentiators

  • Optimized for File Operations: The model significantly improves performance in file-operations depth, achieving 12/12 on a hard gate compared to 9/12 for the stock model. It also drastically reduces unexpected depth side effects from 8 to 0.
  • Efficiency in Depth Tasks: Demonstrates faster wall time (148.91s vs 360.50s) and improved decode speed (13.40 tok/s vs 12.10 tok/s) for depth-related tasks.
  • Research Specialist: This is a research-oriented package designed for specific tool-calling applications, particularly those involving BFCL/OpenAI-style tool calls.
  • Teacher-Free Training: Utilizes a unique training method involving self-generated, checker-passing trajectories and a file-operations depth anchor, without external teacher outputs.

Recommended Use Cases

  • Mac-local tool-calling research: Ideal for developers experimenting with tool-calling agents on macOS.
  • Agentic router component: Suitable for deployment behind an explicit agentic router where specialized file-operation capabilities are required.

Limitations

While excelling in file operations, the model shows a regression in broader tool-calling breadth tasks, making it unsuitable for general-purpose agentic planning without further adaptation. It is not intended as a direct replacement for general-purpose planners like Pace without re-distillation and evaluation on specific intent envelopes.