ThakiCloud/ChainCheck-Judge-Qwen3.5-4B

VISIONPricing:Input $0.4 / Cached $0.08 / Output $0.8Concurrent Unit Cost:1Model Size:4.5BQuant:BF16Context Size:32kTool Calling:SupportedPublished:Oct 5, 2026License:apache-2.0Architecture:Transformer Open Weights Featherless Exclusive Cold

ThakiCloud/ChainCheck-Judge-Qwen3.5-4B is a 4.5 billion parameter Qwen3.5-based model, fine-tuned as an evidence-sufficiency judge for Retrieval-Augmented Generation (RAG) systems. It specializes in evaluating whether retrieved passages are sufficient to answer a question, focusing on the integrity of the reasoning chain rather than just detecting passage edits. With a 32768-token context length, this model provides a log-odds score to determine if passages collectively contain enough information, making it ideal for gating RAG generation to ensure factual accuracy and chain selectivity.

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ChainCheck-Judge-Qwen3.5-4B: RAG Evidence Sufficiency Judge

This model, based on Qwen/Qwen3.5-4B with 4.5 billion parameters and a 32768-token context length, functions as a specialized evidence-sufficiency judge for Retrieval-Augmented Generation (RAG) systems. Unlike standard sufficiency benchmarks that might flag any passage edit, ChainCheck-Judge-Qwen3.5-4B is specifically trained to assess whether the reasoning chain within retrieved passages is intact and sufficient to answer a given question. It provides a log-odds score indicating the sufficiency of passages, allowing for more nuanced evaluation than simple edit detection.

Key Capabilities

  • Chain Selectivity: Significantly improves the ability to distinguish between subtly broken reasoning chains and merely edited-but-valid contexts, as demonstrated by a +0.376 increase in 2Wiki chain selectivity (real entities) compared to the zero-shot base model.
  • RAG Gating: Designed to output a log-odds score that can be used to gate RAG generation, helping systems decide whether to answer, retrieve more information, or abstain.
  • Robust Evaluation: Trained on ChainCheck counterfactual triplets, ensuring it focuses on the integrity of the evidence chain rather than superficial changes.
  • High Nominal AUC: Achieves a 0.983 nominal AUC on 2Wiki real entities, indicating strong overall performance in identifying sufficient evidence.

Good For

  • Improving RAG Accuracy: Developers building RAG systems who need a robust mechanism to ensure the retrieved context genuinely supports the answer.
  • Preventing Hallucinations: Applications where it's critical to avoid generating answers from insufficient or misleading evidence.
  • Evaluating Evidence Chains: Research and development in RAG, particularly for assessing the quality of multi-hop reasoning and evidence integration.
  • English Wikipedia Multi-hop Questions: Optimized for tasks involving English Wikipedia multi-hop questions, such as those found in MuSiQue and 2WikiMultiHopQA datasets.