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sheept • yesterday at 8:20 PM • 3 replies • view on HN

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).

Replies

RandomBK • today at 8:00 AM

How well do we understand the tokenization for Claude? I'd posit that the exact human-representation of this markup is likely irrelevant if it's all being converted into a single token.

xeyownt • today at 8:11 AM

Cannot believe it's efficient. XML is the most verbose and inefficient of communicating anything. The only benefit of XML was to give lifetime work to an army of engineers. The next news will be "Why DTD is so fundamental to Claude".

➕ show 1 reply
bear3r • yesterday at 11:11 PM

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.