GoKawiilAWS engineer tests encoder vs decoder designs for Strands Decider model
Marc Brooker, an AWS engineer, responded to questions about why the strands-decider-2B model uses a modified decoder (LLM) architecture rather than a bidirectional encoder like BERT. He ran comparisons across five model designs, including the existing Qwen3.5-based decoder (v19), two encoder-decoder variants built on T5Gemma 2 at different parameter sizes, and encoder-only models based on T5Gemma. The post presents these as empirical tests of whether bidirectional encoders outperform causal decoders for this classification-style task.