HalBench: I built a custom sycophancy and hallucination benchmark and tested 4 frontier models (Sonnet 4.6, Grok 4.3, GPT 5.4 and Gemini 3.1 Pro), looking for input on what OSS models to run next!

HalBench Results: TL;DR: I built HalBench, an open benchmark for LLM sycophancy and hallucination. 3,200 false-premise prompts × 4 models = 12,800 graded responses. Validated against a human reader on 100 random items. S