"## Pythonic Tool Call Format (Llama-3.2 / Llama-3.3 / Llama-4)\n",
"\n",
"Some Llama models (such as Llama-3.2-1B, Llama-3.2-3B, Llama-3.3-70B, and Llama-4) support a \"pythonic\" tool call format, where the model outputs function calls as Python code, e.g.:\n",
"For more information, refer to Meta’s documentation on [Zero shot function calling](https://github.com/meta-llama/llama-models/blob/main/models/llama4/prompt_format.md#zero-shot-function-calling---system-message).\n",
"\n",
"### How to enable\n",
"- Launch the server with `--tool-call-parser pythonic`\n",
"- You may also specify --chat-template with the improved template for the model (e.g., `--chat-template=examples/chat_template/tool_chat_template_llama4_pythonic.jinja`).\n",
"This is recommended because the model expects a special prompt format to reliably produce valid pythonic tool call outputs. The template ensures that the prompt structure (e.g., special tokens, message boundaries like `<|eom|>`, and function call delimiters) matches what the model was trained or fine-tuned on. If you do not use the correct chat template, tool calling may fail or produce inconsistent results.\n",
"\n",
"#### Forcing Pythonic Tool Call Output Without a Chat Template\n",
"If you don't want to specify a chat template, you must give the model extremely explicit instructions in your messages to enforce pythonic output. For example, for `Llama-3.2-1B-Instruct`, you need:"
"> The model may still default to JSON if it was heavily finetuned on that format. Prompt engineering (including examples) is the only way to increase the chance of pythonic output if you are not using a chat template."
{# Copied from https://github.com/yeqcharlotte/vllm/blob/4fcf68a948bbe0498dc8a98feafa102cfb1dd210/examples/tool_chat_template_llama4_pythonic.jinja to enable better model response. #}
{{- bos_token }}
{%- if custom_tools is defined %}
{%- set tools = custom_tools %}
{%- endif %}
{%- if not tools_in_user_message is defined %}
{%- set tools_in_user_message = false %}
{%- endif %}
{%- if not tools is defined %}
{%- set tools = none %}
{%- endif %}
{#- This block extracts the system message, so we can slot it into the right place. #}
{%- if messages[0]['role'] == 'system' %}
{%- if messages[0]['content'] is string %}
{%- set system_message = messages[0]['content']|trim %}
{%- else %}
{%- set system_message = messages[0]['content'][0]['text']|trim %}
{%- endif %}
{%- set messages = messages[1:] %}
{%- else %}
{%- if tools is not none %}
{#- Add default tool system message when tools are provided #}
{%- set system_message = "You are a helpful assistant with tool calling "
"capabilities. Only reply with a tool call if the function exists in the "
"library provided by the user. If it doesn't exist, just reply directly in "
"natural language. When you receive a tool call response, use the output to "
"format an answer to the original user question." %}
{%- else %}
{%- set system_message = "" %}
{%- endif %}
{%- endif %}
{#- System message if the user supplied one, or if tools are used (default tool system message) #}
{%- if system_message %}
{#- always use user provided system message to override default tool system message #}
{{- "<|header_start|>system<|header_end|>\n\n" }}
{{- system_message }}
{%- if tools is not none and not tools_in_user_message %}
{{- "Tools: You have access to the following tools. You might need to use one "
"or more function/tool calls to fulfill the task. \n"
"If none are needed, then proceed to the response.\n\n"
"Tool Call Syntax: You can call tools using the following syntax:\n"
