Update chat template to use XML tool call format.

chat_template.jinja

@@ -8,12 +8,13 @@
         {{- "\n" }}
         {{- tool | tojson }}
     {%- endfor %}
-    {{- "\n</tools>\n\nFor each function call, return a json object with function name and arguments within <tool_call></tool_call> XML tags:\n<tool_call>\n{\"name\": <function-name>, \"arguments\": <args-json-object>}\n</tool_call><|im_end|>\n" }}
+    {{- "\n</tools>\n\nFor each function call, use this XML format:\n\n<function=function_name>\n  <parameter=param1>value1</parameter>\n  <parameter=param2>value2</parameter>\n</function>\n" }}
 {%- else %}
     {%- if messages[0].role == 'system' %}
         {{- '<|im_start|>system\n' + messages[0].content + '<|im_end|>\n' }}
     {%- endif %}
 {%- endif %}
+
 {%- set ns = namespace(multi_step_tool=true, last_query_index=messages|length - 1) %}
 {%- for message in messages[::-1] %}
     {%- set index = (messages|length - 1) - loop.index0 %}
@@ -57,15 +58,16 @@
                 {%- if tool_call.function %}
                     {%- set tool_call = tool_call.function %}
                 {%- endif %}
-                {{- '<tool_call>\n{"name": "' }}
-                {{- tool_call.name }}
-                {{- '", "arguments": ' }}
+                {{- '<function=' + tool_call.name + '>\n' }}
                 {%- if tool_call.arguments is string %}
-                    {{- tool_call.arguments }}
+                    {%- set args = tool_call.arguments | fromjson %}
                 {%- else %}
-                    {{- tool_call.arguments | tojson }}
+                    {%- set args = tool_call.arguments %}
                 {%- endif %}
-                {{- '}\n</tool_call>' }}
+                {%- for param_name, param_value in args.items() %}
+                    {{- '  <parameter=' + param_name + '>' + param_value + '</parameter>\n' }}
+                {%- endfor %}
+                {{- '</function>' }}
             {%- endfor %}
         {%- endif %}
         {{- '<|im_end|>\n' }}
@@ -86,4 +88,4 @@
     {%- if enable_thinking is defined and enable_thinking is false %}
         {{- '<think>\n\n</think>\n\n' }}
     {%- endif %}
-{%- endif %}
+{%- endif %}