Earlier quoted context omitted.
If the model cannot figure out simple and ubiquitous tools, how is it supposed to figure out complex problems? All of the good models basically work with any harness, including giving them a single "shell command" tool. They can just figure things out.
When it comes to quality of outcome, since at least Feburary, the harness has almost equal, if not more weight than the model itself. It's no longer "which model is the best?" it's "which model + harness is the best?" I get drastically different tool call failure rates using Claude SDK vs OpenCode using Qwen 3.6 models
You can use effectively any harness and get good results. Harnesses are mostly placebo.