Quick doesn't work correctly when used as a "model" in custom agents. It emits librarian tool_call xml tags that go straight to output rather than being intercepted: https://kagi.com/assistant/30414c87-85ce-4a71-be46-e47c41f96ae2
If that link dies, the output after the folded search block is
<tool_call>
{"name": "librarian", "arguments": {"sources": ["https://ordnet.dk/ddo/ordbog?query=%C3%A6rgerlig"]}}
</tool_call>

I assume this also applies to Research, but I don't have access to test it.
I think any of a few things would be reasonable. In rough order of preference:
- Support that style of tool calling and librarian usage when quick is used as the model of custom assistants.
- Change the instructions for quick when used in custom assistants to not use that style of tool call.
- Don't allow using Quick as a custom assistant. This would be reasonable since the built-in assistants kinda seem like alternative presets to custom assistants. OTOH, when custom assistants are basically used as a shortcut for some prompt instructions so that frequent complex query patterns can be expressed in a word or two, it does seem reasonable to want to use that with Quick.