It might be harness or prompting style. Personally I use opencode and my prompting style is very plain and terse . Where tasks are very small. Opus and Sonet to

It might be harness or prompting style. Personally I use opencode and my prompting style is very plain and terse . Where tasks are very small. Opus and Sonet too often are too verbose and go tangent. Where GPT5.5 is much stricter.