> especially considering Horizon Beta does very poorly on tool call and MCP evals in my scenarios GPT-5 does very well on tool calls, my MCP tests and is far b

> especially considering Horizon Beta does very poorly on tool call and MCP evals in my scenarios GPT-5 does very well on tool calls, my MCP tests and is far better than 2.5 Pro in some early agentic coding testing. Seems I was very wrong, though not in the way I would have suspected, as whatever Horizon Alpha and Beta were was not GPT-5 in its entirety, but rather a "submodel" (for lack of a proper term at the moment as it does appear to be distinct from MoE) and limited additionally by having a small context window. Basically, Horizon was an early, very limited preview of what we now get with GPT-5, but the difference between the two is very notable.