ask_engine

THE engine call - ask a model anything. engine = gemini|chatgpt, grounded = true (live search) | false (parametric memory only). Returns answer + citations, plus `sub_queries` on grounded Gemini (the decomposition it fired - no other engine exposes this). Full payload by default; caps are opt-in and any cap that bites is reported in `truncated`. The four gemini_*/chatgpt_* tools are thin aliases of this.

Worked examples for this tool are coming.