[sheept]

XML is a bit more special/first class to Claude because it uses XML for tool calling:

    <antml:invoke name="Read">                                                    
      <antml:parameter name="file_path">/path/to/file</antml:parameter>             
      <antml:parameter name="offset">100</antml:parameter>                          
      <antml:parameter name="limit">50</antml:parameter>                            
    </antml:invoke>

I'm sure Claude can handle any delimiter and pseudo markup you throw at it, but one benefit of XML delimiters over quotation marks is that you repeat the delimiter name at the end, which I'd imagine might help if its contents are long (it certainly helps humans).

[bear3r]

the antml: namespace prefix is doing extra work here too -- even if user input contains invoke tags, they won't collide with tool calls because the namespace differs. not just xml for structure but namespaced xml for isolation.