I use K2 non thinking in OpenCode for coding typically, and I still haven't found a satisfactory chat interface yet so I use K2 Thinking in the default synthetic.new (my AI subscription) chat UI, which is pretty barebones. I'm gonna start trying K2T in OpenCode as well, but I'm actually not a huge fan of thinking models as coding agents — I prefer faster feedback.
I'm also a synthetic.new user, as a backup (and larger contexts) for my Cerebras Coder subscription (zai-glm-4.6). I've been using the free Chatbox client [1] for like ~6 months and it works really well as a daily driver. I've tested the Romanian football player question with 3 different models (K2 Instruct, Deepseek Terminus, GLM 4.6) just now and they all went straight to my Brave MCP tool to query and replied all correctly the same answer.
The issue with OP and GPT-5.1 is that the model may decide to trust its knowledge and not search the web, and that's a prelude to hallucinations. Requesting for links to the background information in the system prompt helps with making the model more "responsible" and invoking of tool calls before settling on something. You can also start your prompt with "search for what Romanian player..."
Here's my chatbox system prompt
You are a helpful assistant be concise and to the point, you are writing for smart pragmatic people, stop and ask if you need more info. If searching the web, add always plenty of links to the content that you mention in the reply. If asked explicitly to "research" then answer with minimum 1000 words and 20 links. Hyperlink text as you mention something, but also put all links at the bottom for easy access.
I checked out chatbox and it looks close to what I've been looking for. Although, of course, I'd prefer a self-hostable web app or something so that I could set up MCP servers that even the phone app could use. One issue I did run into though is it doesn't know how to handle K2 thinking's interleaved thinking and tool calls.
