[Frontend] Added chat templates for LLaMa4 pythonic tool calling (#16463)

Signed-off-by: Ye (Charlotte) Qi <yeq@meta.com>
Co-authored-by: Kai Wu <kaiwu@meta.com>

docs/source/features/tool_calling.md

@@ -245,6 +245,8 @@ Example supported models:
 * `meta-llama/Llama-3.2-3B-Instruct`\* (use with `examples/tool_chat_template_llama3.2_pythonic.jinja`)
 * `Team-ACE/ToolACE-8B` (use with `examples/tool_chat_template_toolace.jinja`)
 * `fixie-ai/ultravox-v0_4-ToolACE-8B` (use with `examples/tool_chat_template_toolace.jinja`)
+* `meta-llama/Llama-4-Scout-17B-16E-Instruct`\* (use with `examples/tool_chat_template_llama4_pythonic.jinja`)
+* `meta-llama/Llama-4-Maverick-17B-128E-Instruct`\* (use with `examples/tool_chat_template_llama4_pythonic.jinja`)
 
 Flags: `--tool-call-parser pythonic --chat-template {see_above}`
 

examples/tool_chat_template_llama4_pythonic.jinja

+{{- 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"
+            "[func_name1(params_name1=params_value1, params_name2=params_value2, ...), ...]\n"
+            "Do not include anything else when calling the tools with the syntax above.\n\n"
+            "Here is a list of functions in JSON format that you can invoke.\n " }}
+        {%- for t in tools %}
+            {{- t | tojson(indent=4) }}
+            {{- "\n\n" }}
+        {%- endfor %}
+    {%- endif %}
+    {{- "<|eot|>" }}
+{%- endif %}
+
+{#- Custom tools are passed in a user message with some extra guidance #}
+{%- if tools_in_user_message and tools is not none %}
+    {#- Extract the first user message so we can plug it in here #}
+    {%- if messages | length != 0 %}
+        {%- if messages[0]['content'] is string %}
+            {%- set first_user_message = messages[0]['content']|trim %}
+        {%- else %}
+            {%- set first_user_message = messages[0]['content'] | selectattr('type', 'equalto', 'text') | map(attribute='text') | map('trim') | join('\n') %}
+        {%- endif %}
+        {%- set messages = messages[1:] %}
+    {%- else %}
+        {{- raise_exception("Cannot put tools in the first user message when there's no first user message!") }}
+    {%- endif %}
+    {{- '<|header_start|>user<|header_end|>\n\n' -}}
+    {{- first_user_message}}
+    {{- "\nHere is a list of functions in JSON format that you can invoke:"}}
+    {%- for t in tools %}
+        {{- t | tojson(indent=4) }}
+        {{- "\n\n" }}
+    {%- endfor %}
+    {{- "Should you decide to return the function call(s), put them in the format "
+        "of [func_name1(params_name1=params_value1, params_name2=params_value2, "
+        "...), ...]\nDo not include anything else when calling the tools with the "
+        "syntax above." }}
+{%- endif %}
+
+{%- for message in messages %}
+    {%- if not (message.role == 'ipython' or message.role == 'tool' or 'tool_calls' in message) %}
+    {{- '<|header_start|>' + message['role'] + '<|header_end|>\n\n' }}
+        {%- if message['content'] is string %}
+            {{- message['content'] }}
+        {%- else %}
+            {%- for content in message['content'] %}
+                {%- if content['type'] == 'image' %}
+                    {{- '<|image|>' }}
+                {%- elif content['type'] == 'text' %}
+                    {{- content['text'] | trim }}
+                {%- endif %}
+            {%- endfor %}
+        {%- endif %}
+        {{- "<|eot|>" }}
+    {%- elif 'tool_calls' in message and message.tool_calls|length > 0 %}
+        {%- set tool_call = message.tool_calls[0].function %}
+        {{- '<|header_start|>assistant<|header_end|>\n\n' -}}
+        {%- if message['content'] is string %}
+            {{- message['content'] }}
+        {%- else %}
+            {%- for content in message['content'] %}
+                {%- if content['type'] == 'image' %}
+                    {{- '<|image|>' }}
+                {%- elif content['type'] == 'text' %}
+                    {{- content['text'] }}
+                {%- endif %}
+            {%- endfor %}
+        {%- endif %}
+        {%- for tool_call in message.tool_calls %}
+            {%- if tool_call.function is defined %}
+                {%- set tool_call = tool_call.function %}
+            {%- endif %}
+            {{- tool_call.name + '(' -}}
+            {%- for param in tool_call.arguments %}
+                {{- param + '=' -}}
+                {{- "%s" | format(tool_call.arguments[param]) -}}
+                {% if not loop.last %}, {% endif %}
+            {%- endfor %}
+            {{- ')' -}}
+            {% if not loop.last %}, {% endif %}
+        {%- endfor %}
+        {{- "<|eom|>" }}
+    {%- elif message.role == "tool" or message.role == "ipython" %}
+        {{- "<|header_start|>ipython<|header_end|>\n\n" }}
+        {%- if message.content is string %}
+            {{- message.content | tojson }}
+        {%- else %}
+            {%- for content in message['content']  %}
+                {%- if content['type']  == 'text' %}
+                    {{- content['text'] | tojson }}
+                {%- endif %}
+            {%- endfor %}
+        {%- endif %}
+        {{- "<|eom|>" }}
+    {%- endif %}
+{%- endfor %}
+{%- if add_generation_prompt %}
+    {{- '<|header_start|>assistant<|header_end|>\n\n' }}
+{%- endif %}

tests/tool_use/conftest.py

@@ -10,10 +10,33 @@ from vllm.platforms import current_platform
 from .utils import ARGS, CONFIGS, ServerConfig
 
 
+# select models to test based on command line arguments
+def pytest_addoption(parser):
+    parser.addoption("--models",
+                     nargs="+",
+                     help="Specify one or more models to test")
+    parser.addoption("--extended",
+                     action="store_true",
+                     default=False,
+                     help="invoke extended tests requiring large GPUs")
+
+
 # for each server config, download the model and return the config
 @pytest.fixture(scope="session", params=CONFIGS.keys())
 def server_config(request):
-    config = CONFIGS[request.param]
+    extended = request.config.getoption("--extended")
+    models = request.config.getoption("--models")
+
+    config_keys_to_test = [
+        key for key in CONFIGS if (models is None or key in models) and (
+            extended or not CONFIGS[key].get("extended", False))
+    ]
+
+    config_key = request.param
+    if config_key not in config_keys_to_test:
+        pytest.skip(f"Skipping config '{config_key}'")
+
+    config = CONFIGS[config_key]
 
     if current_platform.is_rocm() and not config.get("supports_rocm", True):
         pytest.skip("The {} model can't be tested on the ROCm platform".format(

tests/tool_use/utils.py

@@ -16,6 +16,7 @@ class ServerConfig(TypedDict, total=False):
     system_prompt: Optional[str]
     supports_parallel: Optional[bool]
     supports_rocm: Optional[bool]
+    extended: Optional[bool]  # tests do not run in CI automatically
 
 
 def patch_system_prompt(messages: list[dict[str, Any]],
@@ -82,6 +83,21 @@ CONFIGS: dict[str, ServerConfig] = {
         "supports_parallel":
         False,
     },
+    "llama4": {
+        "model":
+        "meta-llama/Llama-4-Scout-17B-16E-Instruct",
+        "arguments": [
+            "--enforce-eager", "--no-enable-prefix-caching",
+            "--tool-call-parser", "pythonic", "--chat-template",
+            str(VLLM_PATH /
+                "examples/tool_chat_template_llama4_pythonic.jinja"), "-tp",
+            "4"
+        ],
+        "supports_parallel":
+        False,
+        "extended":
+        True
+    },
     "mistral": {
         "model":
         "mistralai/Mistral-7B-Instruct-v0.3",

vllm/entrypoints/openai/tool_parsers/pythonic_tool_parser.py

@@ -28,7 +28,7 @@ class _UnexpectedAstError(Exception):
 class PythonicToolParser(ToolParser):
     """
     Tool call parser for models that produce tool calls in a pythonic style,
-    such as Llama 3.2 models.
+    such as Llama 3.2 and Llama 4 models.
 
     Used when --enable-auto-tool-choice --tool-call-parser pythonic are all set
     """