Add simple granite4 tool parser (#36827)

Signed-off-by: Max de Bayser <maxdebayser@gmail.com>
Signed-off-by: Max de Bayser <mbayser@br.ibm.com>

docs/features/tool_calling.md

@@ -219,7 +219,7 @@ Supported models:
 
 * `ibm-granite/granite-4.0-h-small` and other Granite 4.0 models
 
-    Recommended flags: `--tool-call-parser hermes`
+    Recommended flags: `--tool-call-parser granite4`
 
 * `ibm-granite/granite-3.0-8b-instruct`
 

tests/entrypoints/openai/tool_parsers/test_granite4_tool_parser.py

+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+import json
+import random
+from typing import Any
+
+import openai
+import pytest
+from transformers import AutoTokenizer
+
+from vllm.entrypoints.openai.chat_completion.protocol import ChatCompletionRequest
+from vllm.entrypoints.openai.engine.protocol import (
+    DeltaMessage,
+)
+from vllm.tool_parsers.granite4_tool_parser import Granite4ToolParser
+
+from ....utils import RemoteOpenAIServer
+
+MODEL = "ibm-granite/granite-4.0-h-tiny"
+
+
+@pytest.fixture(scope="module")
+def server():
+    model = MODEL
+    args_for_model = [
+        "--enforce-eager",
+        "--enable-auto-tool-choice",
+        "--tool-call-parser",
+        "granite4",
+        "--tokenizer",
+        "ibm-granite/granite-4.0-h-tiny",
+        "--max-model-len",
+        "4096",
+        "--max-num-seqs",
+        "2",
+    ]
+    with RemoteOpenAIServer(model, args_for_model, max_wait_seconds=480) as server:
+        yield server
+
+
+def create_complex_input(create_string_args: bool):
+    coord_arg: dict | str = {
+        "coordinates": [[23.54, 43.1], [-12.2, 54.3], [4, 5]],
+        "coordinate_type": "latlong",
+    }
+    if create_string_args:
+        # test granite behavior
+        coord_arg = json.dumps(coord_arg)
+    return [
+        {"name": "find_bbox", "arguments": coord_arg},
+        {
+            "name": "get_stock_price",
+            "arguments": {
+                "symbol": "AAPL",
+                "start_date": "2021-01-01",
+                "end_date": "2021-12-31",
+            },
+        },
+        {"name": "find_bbox", "arguments": coord_arg},
+    ]
+
+
+def random_chunks(s: str, min_len: int, max_len: int):
+    chunks = []
+    i = 0
+    n = len(s)
+
+    while i < n:
+        size = random.randint(min_len, max_len)
+        chunks.append(s[i : i + size])
+        i += size
+
+    return chunks
+
+
+@pytest.fixture(scope="module")
+def tokenizer():
+    return AutoTokenizer.from_pretrained(MODEL)
+
+
+# create a variety of input chunk sizes
+@pytest.mark.parametrize(
+    "min_chunk, max_chunk",
+    [
+        (1, 1),
+        (1, 2),
+        (5, 7),
+        (6, 20),
+    ],
+)
+def test_tool_call_parser_complex(min_chunk: int, max_chunk: int, tokenizer):
+    input_dicts = create_complex_input(True)
+
+    formatted_tcs = [
+        "<tool_call> " + json.dumps(call) + " </tool_call>" for call in input_dicts
+    ]
+
+    text_messages = [
+        "Here goes the bbox call: \n",
+        " Now the stock price call: \n ",
+        " Now another bbox call: \n ",
+        " See? I'm a helpful assistant.",
+    ]
+
+    test_input = (
+        text_messages[0]
+        + formatted_tcs[0]
+        + text_messages[1]
+        + formatted_tcs[1]
+        + text_messages[2]
+        + formatted_tcs[2]
+        + text_messages[3]
+    )
+
+    any_chat_request = ChatCompletionRequest(
+        seed=42,
+        model=MODEL,
+        messages=[],
+    )
+
+    parser = Granite4ToolParser(tokenizer=tokenizer)
+
+    delta_messages = list[DeltaMessage]()
+    for text in random_chunks(test_input, min_chunk, max_chunk):
+        delta = parser.extract_tool_calls_streaming(
+            previous_text="",
+            current_text="",
+            delta_text=text,
+            previous_token_ids=[],
+            current_token_ids=[],
+            delta_token_ids=[],
+            request=any_chat_request,
+        )
+        if delta is not None:
+            delta_messages.append(delta)
+
+    content = ""
+    tool_calls = list[dict[str, Any]]()
+
+    current_name = "__start__"
+    current_args = ""
+
+    for msg in delta_messages:
+        if msg.content:
+            content += msg.content
+        for tool_call in msg.tool_calls:
+            if delta_func := tool_call.function:
+                if delta_func.name is not None:
+                    if current_name == "__start__":
+                        current_name = delta_func.name
+
+                    if delta_func.name != current_name:
+                        tool_calls.append(
+                            {
+                                "name": current_name,
+                                "arguments": json.loads(current_args),
+                            }
+                        )
+                        current_name = delta_func.name
+                        current_args = ""
+
+                if delta_func.arguments:
+                    current_args += delta_func.arguments
+
+    if current_name != "__start__":
+        tool_calls.append({"name": current_name, "arguments": json.loads(current_args)})
+
+    assert content == "".join(text_messages)
+    assert tool_calls == create_complex_input(False)
+
+
+tools = [
+    {
+        "type": "function",
+        "function": {
+            "name": "get_acme_region_name_for_transaction_id",
+            "description": "Returns ACME transaction/transaction ID information"
+            " including ACME regions\n\nArgs:\n    start_time "
+            "(str): Start date and time in datetime format "
+            '"%Y-%m-%dT%H:%M:%S.%f"\n    end_time (str): End '
+            "date and time in datetime format "
+            '"%Y-%m-%dT%H:%M:%S.%f"\n    size (int, optional): '
+            "Number of ACME Transaction IDs to return\n    "
+            "order (str, optional): Sort by most run "
+            "transaction IDs. The value can be 'asc' for "
+            "ascending or 'desc' for descending\n    "
+            "transaction_id (str, optional): ACME Transaction "
+            "ID to filter on\n    acme_region (str, optional): "
+            "ACME Region to filter on\nReturns:\n    - A "
+            "dictionary containing a list of ACME transaction "
+            "ids and the ACME regions they run in:\n        {\n"
+            '            "Number of transaction IDs"   : int,\n'
+            '            "Total transaction IDs available": int'
+            ',\n            "ACME Transaction IDs": [\n        '
+            '        {\n                    "Transaction ID": '
+            'str,\n                    "Number of runs": int,\n'
+            '                    "ACME Regions": [str],\n      '
+            "          },\n                ...\n            ],"
+            '\n            "Start time"         : datetime,\n '
+            '           "End time"           : datetime,\n    '
+            '        "Order"              : str\n        }\n  '
+            "  - If no ACME region found for transaction id, "
+            'returns:\n        {"Success": "No ACME region '
+            'found for transaction id."}\n    - If an error '
+            'occurs, returns:\n        {"Error": "{exception'
+            ' message}"}',
+            "parameters": {
+                "properties": {
+                    "start_time": {},
+                    "end_time": {},
+                    "size": {"default": 500},
+                    "order": {"default": "desc"},
+                    "transaction_id": {"default": None},
+                    "acme_region": {"default": None},
+                },
+                "required": ["start_time", "end_time"],
+                "type": "object",
+            },
+        },
+    }
+]
+
+tools2 = [
+    {
+        "type": "function",
+        "function": {
+            "name": "get_current_weather",
+            "description": "Get the current weather",
+            "parameters": {
+                "type": "object",
+                "properties": {
+                    "location": {
+                        "description": "The city and state, e.g. San Francisco, CA",
+                        "type": "string",
+                    }
+                },
+                "required": ["location"],
+            },
+        },
+    },
+    {
+        "type": "function",
+        "function": {
+            "name": "get_stock_price",
+            "description": "Retrieves the current stock price for a given "
+            "ticker symbol. The ticker symbol must be a valid "
+            "symbol for a publicly traded company on a major US"
+            " stock exchange like NYSE or NASDAQ. The tool will"
+            " return the latest trade price in USD. It should "
+            "be used when the user asks about the current or "
+            "most recent price of a specific stock. It will not"
+            " provide any other information about the stock or"
+            " company.",
+            "parameters": {
+                "type": "object",
+                "properties": {
+                    "ticker": {
+                        "description": "The stock ticker symbol, e.g."
+                        " AAPL for Apple Inc.",
+                        "type": "string",
+                    }
+                },
+            },
+        },
+    },
+]
+
+messages = [
+    {
+        "content": "\n\nSystem: You are a helpful, precise, and methodical AI"
+        " assistant that uses tool outputs provided inline.\nAlways"
+        " assume the current datetime is 2026-01-29T13:59:09.238901"
+        "+00:00.\n\nIf you receive a ToolMessage with `tool_call_id"
+        '` equal to "get_time_range" (or "time_range_tool"), you '
+        "MUST:\n  1. Parse that JSON and use the values `start` and"
+        " `end` directly when calling other tools.\n  2. Do not "
+        "re-call or re-compute the time range.\n  3. Pass resolved "
+        "values (ISO strings) as arguments to any subsequent tool "
+        "(do not pass function metadata or placeholders).\n  4. If "
+        "a tool requires datetime objects rather than strings, "
+        "convert the ISO strings into language-native datetime "
+        "objects before invoking.\n\nAlways return fully resolved "
+        "arguments in correct types (e.g., ISO datetime strings or"
+        " datetime objects) and never include placeholders like "
+        '"<start>".\n\n',
+        "role": "system",
+    },
+    {
+        "content": "What are the transaction IDs that ran in the"
+        " ACME region A9345 over the last two months?",
+        "role": "user",
+    },
+    {
+        "content": '["2026-01-26T09: 51: 55.467722Z", "2026-01-27T09: 51: 55.467722Z"]',
+        "role": "tool",
+        "tool_call_id": "time_range_tool",
+    },
+]
+messages2 = [{"role": "user", "content": "What's stock price for IBM?"}]
+
+messages3 = [{"role": "user", "content": "What's the current weather in New York?"}]
+
+
+def get_args(client: openai.OpenAI, _tools, _messages, _stop):
+    response = client.chat.completions.create(
+        model=MODEL,
+        messages=_messages,
+        temperature=0,
+        tools=_tools,
+        max_tokens=200,
+        stop=_stop,
+        tool_choice="auto",
+    )
+
+    return response.choices[0].message.tool_calls[0].function.arguments
+
+
+async def get_args_streaming(
+    async_client: openai.AsyncOpenAI, _tools, _messages, _stop
+):
+    stream = await async_client.chat.completions.create(
+        model=MODEL,
+        messages=_messages,
+        temperature=0,
+        tools=_tools,
+        max_tokens=200,
+        stop=_stop,
+        tool_choice="auto",
+        stream=True,
+    )
+    full_call = []
+    async for chunk in stream:
+        tc = chunk.choices[0].delta.tool_calls
+        if tc and tc[0].function.arguments:
+            full_call.append(tc[0].function.arguments)
+    return "".join(full_call)
+
+
+async def run_scenario(server: RemoteOpenAIServer, _tools, _messages, _stop):
+    non_streaming = get_args(server.get_client(), _tools, _messages, _stop)
+    json.loads(non_streaming)  # verify that it is json loadable
+    streaming = await get_args_streaming(
+        server.get_async_client(), _tools, _messages, _stop
+    )
+    json.loads(streaming)
+    assert non_streaming == streaming, f"{non_streaming=}, {streaming=}"
+
+
+@pytest.mark.asyncio
+async def test_stop_sequence_interference(server: RemoteOpenAIServer):
+    print("Testing scenario 1")
+    await run_scenario(server, tools, messages, "veroniqueprattyushveroniqueprattyush")
+
+    print("Testing scenario 2")
+    await run_scenario(
+        server, tools2, messages2, "veroniqueprattyushveroniqueprattyush"
+    )
+
+    print("Testing scenario 3")
+    await run_scenario(server, tools2, messages3, "prattyush")

tests/entrypoints/openai/tool_parsers/test_hermes_tool_parser.py

@@ -3,29 +3,22 @@
 
 import json
 
+import openai
 import pytest
+import pytest_asyncio
+from huggingface_hub import snapshot_download
+from typing_extensions import TypedDict
 
 from vllm.entrypoints.openai.chat_completion.protocol import ChatCompletionRequest
 from vllm.tokenizers import TokenizerLike
+from vllm.tool_parsers.abstract_tool_parser import ToolParser
+from vllm.tool_parsers.granite4_tool_parser import Granite4ToolParser
 from vllm.tool_parsers.hermes_tool_parser import Hermes2ProToolParser
 
 from ....utils import RemoteOpenAIServer
 
-MODEL_NAME = "meta-llama/Llama-3.2-1B-Instruct"
 LORA_MODEL = "minpeter/LoRA-Llama-3.2-1B-tool-vllm-ci"
 
-SERVER_ARGS = [
-    "--enforce-eager",
-    "--enable-auto-tool-choice",
-    "--tool-call-parser",
-    "hermes",
-    "--enable-lora",
-    "--lora-modules",
-    f"{LORA_MODEL}={LORA_MODEL}",
-    "--tokenizer",
-    f"{LORA_MODEL}",
-]
-
 TOOLS = [
     {
         "type": "function",
@@ -50,6 +43,75 @@ TOOLS = [
     }
 ]
 
+
+class ServerConfig(TypedDict, total=False):
+    model: str
+    arguments: list[str]
+    model_arg: str
+    tool_parser: ToolParser
+
+
+CONFIGS: dict[str, ServerConfig] = {
+    "llama": {
+        "model": "meta-llama/Llama-3.2-1B-Instruct",
+        "arguments": [
+            "--enforce-eager",
+            "--enable-auto-tool-choice",
+            "--tool-call-parser",
+            "hermes",
+            "--enable-lora",
+            "--lora-modules",
+            f"{LORA_MODEL}={LORA_MODEL}",
+            "--tokenizer",
+            f"{LORA_MODEL}",
+        ],
+        "model_arg": LORA_MODEL,
+        "tool_parser": Hermes2ProToolParser,
+    },
+    "granite4": {
+        "model": "ibm-granite/granite-4.0-h-tiny",
+        "arguments": [
+            "--enforce-eager",
+            "--enable-auto-tool-choice",
+            "--tool-call-parser",
+            "granite4",
+            "--tokenizer",
+            "ibm-granite/granite-4.0-h-tiny",
+            "--max-model-len",
+            "4096",
+            "--max-num-seqs",
+            "2",
+        ],
+        "model_arg": "ibm-granite/granite-4.0-h-tiny",
+        "tool_parser": Granite4ToolParser,
+    },
+}
+
+
+# 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]
+
+    # download model and tokenizer using transformers
+    snapshot_download(config["model"])
+    yield CONFIGS[request.param]
+
+
+@pytest.fixture(scope="module")
+def server(request, server_config: ServerConfig):
+    model = server_config["model"]
+    args_for_model = server_config["arguments"]
+    with RemoteOpenAIServer(model, args_for_model, max_wait_seconds=480) as server:
+        yield server
+
+
+@pytest_asyncio.fixture
+async def client(server: RemoteOpenAIServer):
+    async with server.get_async_client() as async_client:
+        yield async_client
+
+
 PRODUCT_TOOLS = [
     {
         "type": "function",
@@ -87,186 +149,182 @@ PRODUCT_MESSAGES = [
 
 
 @pytest.mark.asyncio
-async def test_non_streaming_tool_call():
+async def test_non_streaming_tool_call(
+    client: openai.AsyncOpenAI, server_config: ServerConfig
+):
     """Test tool call in non-streaming mode."""
-    with RemoteOpenAIServer(MODEL_NAME, SERVER_ARGS) as server:
-        client = server.get_async_client()
-
-        response = await client.chat.completions.create(
-            model=LORA_MODEL,
-            messages=MESSAGES,
-            tools=TOOLS,
-            tool_choice="auto",
-            temperature=0.0,
-        )
 
-        assert response.choices
-        choice = response.choices[0]
-        message = choice.message
+    response = await client.chat.completions.create(
+        model=server_config["model_arg"],
+        messages=MESSAGES,
+        tools=TOOLS,
+        tool_choice="auto",
+        temperature=0.0,
+    )
+
+    assert response.choices
+    choice = response.choices[0]
+    message = choice.message
 
-        assert choice.finish_reason == "tool_calls"
-        assert message.tool_calls is not None
+    assert choice.finish_reason == "tool_calls"
+    assert message.tool_calls is not None
 
-        tool_call = message.tool_calls[0]
-        assert tool_call.type == "function"
-        assert tool_call.function.name == "get_current_weather"
+    tool_call = message.tool_calls[0]
+    assert tool_call.type == "function"
+    assert tool_call.function.name == "get_current_weather"
 
-        arguments = json.loads(tool_call.function.arguments)
-        assert "location" in arguments
-        assert "Boston" in arguments["location"]
-        print("\n[Non-Streaming Test Passed]")
-        print(f"Tool Call: {tool_call.function.name}")
-        print(f"Arguments: {arguments}")
+    arguments = json.loads(tool_call.function.arguments)
+    assert "location" in arguments
+    assert "Boston" in arguments["location"]
+    print("\n[Non-Streaming Test Passed]")
+    print(f"Tool Call: {tool_call.function.name}")
+    print(f"Arguments: {arguments}")
 
 
 @pytest.mark.asyncio
-async def test_streaming_tool_call():
+async def test_streaming_tool_call(
+    client: openai.AsyncOpenAI, server_config: ServerConfig
+):
     """Test tool call in streaming mode."""
-    with RemoteOpenAIServer(MODEL_NAME, SERVER_ARGS) as server:
-        client = server.get_async_client()
-
-        stream = await client.chat.completions.create(
-            model=LORA_MODEL,
-            messages=MESSAGES,
-            tools=TOOLS,
-            tool_choice="auto",
-            temperature=0.0,
-            stream=True,
-        )
 
-        tool_call_chunks = {}
-        async for chunk in stream:
-            if not chunk.choices:
-                continue
+    stream = await client.chat.completions.create(
+        model=server_config["model_arg"],
+        messages=MESSAGES,
+        tools=TOOLS,
+        tool_choice="auto",
+        temperature=0.0,
+        stream=True,
+    )
+
+    tool_call_chunks = {}
+    async for chunk in stream:
+        if not chunk.choices:
+            continue
 
-            delta = chunk.choices[0].delta
-            if not delta or not delta.tool_calls:
-                continue
+        delta = chunk.choices[0].delta
+        if not delta or not delta.tool_calls:
+            continue
 
-            for tool_chunk in delta.tool_calls:
-                index = tool_chunk.index
-                if index not in tool_call_chunks:
-                    tool_call_chunks[index] = {"name": "", "arguments": ""}
+        for tool_chunk in delta.tool_calls:
+            index = tool_chunk.index
+            if index not in tool_call_chunks:
+                tool_call_chunks[index] = {"name": "", "arguments": ""}
 
-                if tool_chunk.function.name:
-                    tool_call_chunks[index]["name"] += tool_chunk.function.name
-                if tool_chunk.function.arguments:
-                    tool_call_chunks[index]["arguments"] += (
-                        tool_chunk.function.arguments
-                    )
+            if tool_chunk.function.name:
+                tool_call_chunks[index]["name"] += tool_chunk.function.name
+            if tool_chunk.function.arguments:
+                tool_call_chunks[index]["arguments"] += tool_chunk.function.arguments
 
-        assert len(tool_call_chunks) == 1
-        reconstructed_tool_call = tool_call_chunks[0]
+    assert len(tool_call_chunks) == 1
+    reconstructed_tool_call = tool_call_chunks[0]
 
-        assert reconstructed_tool_call["name"] == "get_current_weather"
+    assert reconstructed_tool_call["name"] == "get_current_weather"
 
-        arguments = json.loads(reconstructed_tool_call["arguments"])
-        assert "location" in arguments
-        assert "Boston" in arguments["location"]
-        print("\n[Streaming Test Passed]")
-        print(f"Reconstructed Tool Call: {reconstructed_tool_call['name']}")
-        print(f"Reconstructed Arguments: {arguments}")
+    arguments = json.loads(reconstructed_tool_call["arguments"])
+    assert "location" in arguments
+    assert "Boston" in arguments["location"]
+    print("\n[Streaming Test Passed]")
+    print(f"Reconstructed Tool Call: {reconstructed_tool_call['name']}")
+    print(f"Reconstructed Arguments: {arguments}")
 
 
 @pytest.mark.asyncio
-async def test_non_streaming_product_tool_call():
+async def test_non_streaming_product_tool_call(
+    client: openai.AsyncOpenAI, server_config: ServerConfig
+):
     """Test tool call integer and boolean parameters in non-streaming mode."""
-    with RemoteOpenAIServer(MODEL_NAME, SERVER_ARGS) as server:
-        client = server.get_async_client()
-
-        response = await client.chat.completions.create(
-            model=LORA_MODEL,
-            messages=PRODUCT_MESSAGES,
-            tools=PRODUCT_TOOLS,
-            tool_choice="auto",
-            temperature=0.66,
-        )
 
-        assert response.choices
-        choice = response.choices[0]
-        message = choice.message
+    response = await client.chat.completions.create(
+        model=server_config["model_arg"],
+        messages=PRODUCT_MESSAGES,
+        tools=PRODUCT_TOOLS,
+        tool_choice="auto",
+        temperature=0.66,
+    )
+
+    assert response.choices
+    choice = response.choices[0]
+    message = choice.message
 
-        assert choice.finish_reason == "tool_calls"
-        assert message.tool_calls is not None
+    assert choice.finish_reason == "tool_calls"
+    assert message.tool_calls is not None
 
-        tool_call = message.tool_calls[0]
-        assert tool_call.type == "function"
-        assert tool_call.function.name == "get_product_info"
+    tool_call = message.tool_calls[0]
+    assert tool_call.type == "function"
+    assert tool_call.function.name == "get_product_info"
 
-        arguments = json.loads(tool_call.function.arguments)
-        assert "product_id" in arguments
-        assert "inserted" in arguments
+    arguments = json.loads(tool_call.function.arguments)
+    assert "product_id" in arguments
+    assert "inserted" in arguments
 
-        product_id = arguments.get("product_id")
-        inserted = arguments.get("inserted")
+    product_id = arguments.get("product_id")
+    inserted = arguments.get("inserted")
 
-        assert isinstance(product_id, int)
-        assert product_id == 7355608
-        assert isinstance(inserted, bool)
-        assert inserted is True
+    assert isinstance(product_id, int)
+    assert product_id == 7355608
+    assert isinstance(inserted, bool)
+    assert inserted is True
 
-        print("\n[Non-Streaming Product Test Passed]")
-        print(f"Tool Call: {tool_call.function.name}")
-        print(f"Arguments: {arguments}")
+    print("\n[Non-Streaming Product Test Passed]")
+    print(f"Tool Call: {tool_call.function.name}")
+    print(f"Arguments: {arguments}")
 
 
 @pytest.mark.asyncio
-async def test_streaming_product_tool_call():
+async def test_streaming_product_tool_call(
+    client: openai.AsyncOpenAI, server_config: ServerConfig
+):
     """Test tool call integer and boolean parameters in streaming mode."""
-    with RemoteOpenAIServer(MODEL_NAME, SERVER_ARGS) as server:
-        client = server.get_async_client()
-
-        stream = await client.chat.completions.create(
-            model=LORA_MODEL,
-            messages=PRODUCT_MESSAGES,
-            tools=PRODUCT_TOOLS,
-            tool_choice="auto",
-            temperature=0.66,
-            stream=True,
-        )
 
-        tool_call_chunks = {}
-        async for chunk in stream:
-            if not chunk.choices:
-                continue
+    stream = await client.chat.completions.create(
+        model=server_config["model_arg"],
+        messages=PRODUCT_MESSAGES,
+        tools=PRODUCT_TOOLS,
+        tool_choice="auto",
+        temperature=0.66,
+        stream=True,
+    )
+
+    tool_call_chunks = {}
+    async for chunk in stream:
+        if not chunk.choices:
+            continue
 
-            delta = chunk.choices[0].delta
-            if not delta or not delta.tool_calls:
-                continue
+        delta = chunk.choices[0].delta
+        if not delta or not delta.tool_calls:
+            continue
 
-            for tool_chunk in delta.tool_calls:
-                index = tool_chunk.index
-                if index not in tool_call_chunks:
-                    tool_call_chunks[index] = {"name": "", "arguments": ""}
+        for tool_chunk in delta.tool_calls:
+            index = tool_chunk.index
+            if index not in tool_call_chunks:
+                tool_call_chunks[index] = {"name": "", "arguments": ""}
 
-                if tool_chunk.function.name:
-                    tool_call_chunks[index]["name"] += tool_chunk.function.name
-                if tool_chunk.function.arguments:
-                    tool_call_chunks[index]["arguments"] += (
-                        tool_chunk.function.arguments
-                    )
+            if tool_chunk.function.name:
+                tool_call_chunks[index]["name"] += tool_chunk.function.name
+            if tool_chunk.function.arguments:
+                tool_call_chunks[index]["arguments"] += tool_chunk.function.arguments
 
-        assert len(tool_call_chunks) == 1
-        reconstructed_tool_call = tool_call_chunks[0]
+    assert len(tool_call_chunks) == 1
+    reconstructed_tool_call = tool_call_chunks[0]
 
-        assert reconstructed_tool_call["name"] == "get_product_info"
+    assert reconstructed_tool_call["name"] == "get_product_info"
 
-        arguments = json.loads(reconstructed_tool_call["arguments"])
-        assert "product_id" in arguments
-        assert "inserted" in arguments
+    arguments = json.loads(reconstructed_tool_call["arguments"])
+    assert "product_id" in arguments
+    assert "inserted" in arguments
 
-        # Handle type coercion for streaming test as well
-        product_id = arguments.get("product_id")
-        inserted = arguments.get("inserted")
+    # Handle type coercion for streaming test as well
+    product_id = arguments.get("product_id")
+    inserted = arguments.get("inserted")
 
-        assert isinstance(product_id, int)
-        assert product_id == 7355608
-        assert isinstance(inserted, bool)
-        assert inserted is True
+    assert isinstance(product_id, int)
+    assert product_id == 7355608
+    assert isinstance(inserted, bool)
+    assert inserted is True
 
-        print("\n[Streaming Product Test Passed]")
-        print(f"Reconstructed Tool Call: {reconstructed_tool_call['name']}")
-        print(f"Reconstructed Arguments: {arguments}")
+    print("\n[Streaming Product Test Passed]")
+    print(f"Reconstructed Tool Call: {reconstructed_tool_call['name']}")
+    print(f"Reconstructed Arguments: {arguments}")
 
 
 @pytest.fixture
@@ -276,9 +334,10 @@ def qwen_tokenizer() -> TokenizerLike:
     return get_tokenizer("Qwen/Qwen3-32B")
 
 
-@pytest.fixture
-def hermes_parser(qwen_tokenizer: TokenizerLike) -> Hermes2ProToolParser:
-    return Hermes2ProToolParser(qwen_tokenizer)
+@pytest.fixture(params=CONFIGS.keys())
+def hermes_parser(request, qwen_tokenizer: TokenizerLike) -> ToolParser:
+    config = CONFIGS[request.param]
+    return config["tool_parser"](qwen_tokenizer)
 
 
 @pytest.fixture
@@ -292,7 +351,7 @@ def any_chat_request() -> ChatCompletionRequest:
 
 def test_hermes_parser_streaming_just_forward_text(
     qwen_tokenizer: TokenizerLike,
-    hermes_parser: Hermes2ProToolParser,
+    hermes_parser: ToolParser,
     any_chat_request: ChatCompletionRequest,
 ) -> None:
     text = """This is some prior text that has nothing to do with tool calling."""
@@ -324,7 +383,7 @@ def test_hermes_parser_streaming_just_forward_text(
 
 def test_hermes_parser_streaming_failure_case_bug_19056(
     qwen_tokenizer: TokenizerLike,
-    hermes_parser: Hermes2ProToolParser,
+    hermes_parser: ToolParser,
     any_chat_request: ChatCompletionRequest,
 ) -> None:
     text = """<tool_call>
@@ -358,7 +417,7 @@ def test_hermes_parser_streaming_failure_case_bug_19056(
 
 def test_hermes_parser_streaming(
     qwen_tokenizer: TokenizerLike,
-    hermes_parser: Hermes2ProToolParser,
+    hermes_parser: ToolParser,
     any_chat_request: ChatCompletionRequest,
 ) -> None:
     text = '<tool_call>\
@@ -387,16 +446,20 @@ def test_hermes_parser_streaming(
             delta_messages.append(delta)
     print(delta_messages)
     assert delta_messages[0].tool_calls[0].function.name == "get_current_temperature"
-    tool_call_args = "".join(
-        delta.tool_calls[0].function.arguments or "" for delta in delta_messages
-    )
-    assert tool_call_args == (
-        '{"location":"San Francisco, California, United States", "unit": "celsius"}'
+    # load to normalize whitespace
+    tool_call_args = json.loads(
+        "".join(
+            delta.tool_calls[0].function.arguments or "" for delta in delta_messages
+        )
     )
+    assert tool_call_args == {
+        "location": "San Francisco, California, United States",
+        "unit": "celsius",
+    }
 
 
 def test_hermes_parser_non_streaming_no_tool_call(
-    hermes_parser: Hermes2ProToolParser,
+    hermes_parser: ToolParser,
     any_chat_request: ChatCompletionRequest,
 ) -> None:
     text = """This is not a tool call."""
@@ -410,7 +473,7 @@ def test_hermes_parser_non_streaming_no_tool_call(
 
 
 def test_hermes_parser_non_streaming_tool_call_between_tags(
-    hermes_parser: Hermes2ProToolParser,
+    hermes_parser: ToolParser,
     any_chat_request: ChatCompletionRequest,
 ) -> None:
     text = """<tool_call>
@@ -428,9 +491,12 @@ def test_hermes_parser_non_streaming_tool_call_between_tags(
 
 
 def test_hermes_parser_non_streaming_tool_call_until_eos(
-    hermes_parser: Hermes2ProToolParser,
+    hermes_parser: ToolParser,
     any_chat_request: ChatCompletionRequest,
 ) -> None:
+    if isinstance(hermes_parser, Granite4ToolParser):
+        pytest.skip(reason="The Granite4 tool parser enforces a complete response")
+
     text = """<tool_call>
 {"name": "final_answer", "arguments": {"trigger": true}}"""
     tool_call = hermes_parser.extract_tool_calls(
@@ -445,7 +511,7 @@ def test_hermes_parser_non_streaming_tool_call_until_eos(
 
 
 def test_hermes_parser_non_streaming_tool_call_invalid_json(
-    hermes_parser: Hermes2ProToolParser,
+    hermes_parser: ToolParser,
     any_chat_request: ChatCompletionRequest,
 ) -> None:
     # Missing closing brace to trigger exception

vllm/tool_parsers/__init__.py

@@ -54,6 +54,10 @@ _TOOL_PARSERS_TO_REGISTER = {
         "granite_tool_parser",
         "GraniteToolParser",
     ),
+    "granite4": (
+        "granite4_tool_parser",
+        "Granite4ToolParser",
+    ),
     "hermes": (
         "hermes_tool_parser",
         "Hermes2ProToolParser",

vllm/tool_parsers/granite4_tool_parser.py

+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+import json
+from collections.abc import Sequence
+from typing import Any, Protocol, TypeVar
+
+import regex as re
+
+from vllm.entrypoints.chat_utils import make_tool_call_id
+from vllm.entrypoints.openai.chat_completion.protocol import (
+    ChatCompletionRequest,
+)
+from vllm.entrypoints.openai.engine.protocol import (
+    DeltaFunctionCall,
+    DeltaMessage,
+    DeltaToolCall,
+    ExtractedToolCallInformation,
+    FunctionCall,
+    ToolCall,
+)
+from vllm.logger import init_logger
+from vllm.tokenizers import TokenizerLike
+from vllm.tool_parsers.abstract_tool_parser import (
+    ToolParser,
+)
+
+logger = init_logger(__name__)
+
+
+def dump_args(args: None | dict[str, Any] | str) -> str | None:
+    if args is None or isinstance(args, str):
+        return args
+    else:
+        return json.dumps(args, ensure_ascii=False)
+
+
+class _FunctionCallCtor(Protocol):
+    def __init__(self, *, name: str, arguments: str | None): ...
+
+
+FuncT = TypeVar("FuncT", bound=_FunctionCallCtor)
+
+
+class Granite4ToolParser(ToolParser):
+    def __init__(self, tokenizer: TokenizerLike):
+        super().__init__(tokenizer)
+
+        self.prev_tool_call_arr: list[dict] = []
+        self.current_tool_id: int = -1
+        self.streamed_args_for_tool = list[str]()
+
+        self.look_ahead = ""
+        self.in_tc = False
+
+        self.tc_start = "<tool_call>"
+        self.tc_end = "</tool_call>"
+        self.start_regex = re.compile(self.tc_start)
+        self.end_regex = re.compile(self.tc_end)
+
+    def adjust_request(self, request: ChatCompletionRequest) -> ChatCompletionRequest:
+        request = super().adjust_request(request)
+        if request.tools and request.tool_choice != "none":
+            # do not skip special tokens because the tool_call tokens are
+            # marked "special" in some models. Since they are skipped
+            # prior to the call to the tool parser, it breaks tool calling.
+            request.skip_special_tokens = False
+        return request
+
+    def _collect_results(
+        self, text_segments: list[str], tc_segments: list[str], cls: type[FuncT]
+    ) -> tuple[str, list[FuncT]]:
+        tool_calls_json: list[dict[str, Any]] = [
+            json.loads(tc_text) for tc_text in tc_segments
+        ]
+        tool_calls = []
+        for tc in tool_calls_json:
+            assert isinstance(tc, dict)
+            self.prev_tool_call_arr.append(tc)
+            tool_calls.append(
+                cls(
+                    name=tc["name"],
+                    arguments=dump_args(tc["arguments"]),
+                )
+            )
+        return "".join(text_segments), tool_calls
+
+    def extract_tool_calls(
+        self,
+        model_output: str,
+        request: ChatCompletionRequest,
+    ) -> ExtractedToolCallInformation:
+        msg = ExtractedToolCallInformation(
+            tools_called=False, tool_calls=[], content=model_output
+        )
+        try:
+            delimiters = [("TC_START", self.tc_start), ("TC_END", self.tc_end)]
+            pattern = "|".join(f"(?P<{name}>{pattern})" for name, pattern in delimiters)
+            regex = re.compile(pattern)
+
+            text_segments = list[str]()
+            tc_segments = list[str]()
+            last_cut_loc = 0
+
+            for match in regex.finditer(model_output):
+                match_type = match.lastgroup
+                if match_type == "TC_START":
+                    assert not self.in_tc, "Two tool call start tokens found in a row"
+                    if preceding_text := model_output[last_cut_loc : match.start()]:
+                        text_segments.append(preceding_text)
+                    self.in_tc = True
+                elif match_type == "TC_END":
+                    assert self.in_tc, (
+                        "Tool call end token found without corresponding start token"
+                    )
+                    tool_text = model_output[last_cut_loc : match.start()]
+                    assert tool_text, (
+                        "Expected the model to generate text between tool call tokens"
+                    )
+                    tc_segments.append(tool_text)
+                    self.in_tc = False
+                else:
+                    raise ValueError("Unexpected match")
+                last_cut_loc = match.end()
+            assert not self.in_tc, "The model generated an incomplete tool call"
+            if final_text := model_output[last_cut_loc:]:
+                text_segments.append(final_text)
+
+            content, tool_call_funcs = self._collect_results(
+                text_segments, tc_segments, FunctionCall
+            )
+            tool_calls = [
+                ToolCall(
+                    type="function",
+                    function=func,
+                )
+                for func in tool_call_funcs
+            ]
+            msg.tools_called = bool(tool_calls)
+            msg.tool_calls = tool_calls
+            msg.content = content or None
+        except Exception:
+            logger.exception("Error in extracting tool call from response.")
+        return msg
+
+    def _tool_extraction_step(
+        self,
+        delta_text: str,
+    ) -> tuple[bool, str, str]:
+        start_token_pos = start_token_end = end_token_pos = end_token_end = -1
+
+        if start_match := self.start_regex.search(delta_text, partial=True):
+            if not start_match.partial:
+                start_token_pos, start_token_end = start_match.span()
+            elif start_match.end() > start_match.start():
+                start_token_pos = -2
+
+        if end_match := self.end_regex.search(delta_text):
+            end_token_pos, end_token_end = end_match.span()
+
+        # Done means that we've exhausted the current buffer
+        # and need more output from the model
+        done = True
+        content = tc_text = ""
+
+        if start_token_pos < 0:
+            # just streaming text so far
+            if start_token_pos == -2:
+                # There is a partial match
+                content = delta_text[: start_match.start()]
+                self.look_ahead = delta_text[start_match.start() :]
+            else:
+                content = delta_text
+
+        elif not self.in_tc:
+            # we're entering a new tool call
+            self.in_tc = True
+
+            content = delta_text[:start_token_pos]
+            if end_token_pos > 0:
+                self.start_in_tc = False
+                tc_text = delta_text[start_token_end:end_token_pos]
+                self.look_ahead = delta_text[end_token_end:]
+                done = False  # There could be more content already buffered
+            else:
+                self.look_ahead = delta_text[start_token_pos:]
+
+        elif end_token_pos < 0:
+            # we're in between the start and the end token
+            assert self.in_tc
+            self.look_ahead = delta_text
+        else:
+            # We have found the end
+            assert self.in_tc
+            tc_text = delta_text[start_token_end:end_token_pos]
+            self.in_tc = False
+            self.look_ahead = delta_text[end_token_end:]
+            done = False  # There could be more content already buffered
+        return done, content, tc_text
+
+    def extract_tool_calls_streaming(
+        self,
+        previous_text: str,
+        current_text: str,
+        delta_text: str,
+        previous_token_ids: Sequence[int],
+        current_token_ids: Sequence[int],
+        delta_token_ids: Sequence[int],
+        request: ChatCompletionRequest,
+    ) -> DeltaMessage | None:
+        try:
+            done = False
+            text_segments = list[str]()
+            tc_segments = list[str]()
+
+            while not done:
+                delta_text = self.look_ahead + delta_text
+                self.look_ahead = ""
+                done, content, tc_text = self._tool_extraction_step(delta_text)
+                if content:
+                    text_segments.append(content)
+                if tc_text:
+                    tc_segments.append(tc_text)
+                delta_text = ""
+
+            content, tool_call_funcs = self._collect_results(
+                text_segments, tc_segments, DeltaFunctionCall
+            )
+
+            delta_tool_calls = list[DeltaToolCall]()
+            for function in tool_call_funcs:
+                self.current_tool_id += 1
+                delta_tool_calls.append(
+                    DeltaToolCall(
+                        id=make_tool_call_id(),
+                        type="function",
+                        index=self.current_tool_id,
+                        function=function.model_dump(exclude_none=True),
+                    )
+                )
+                self.streamed_args_for_tool.append(function.arguments or "")
+
+            assert self.current_tool_id + 1 == len(self.prev_tool_call_arr)
+            assert self.current_tool_id + 1 == len(self.streamed_args_for_tool)
+
+            msg = DeltaMessage(content=content or None, tool_calls=delta_tool_calls)
+            if msg.content or msg.tool_calls:
+                return msg
+
+        except Exception:
+            logger.exception("Error trying to handle streaming tool call.")
+        return None