Merge pull request #2051 from pipecat-ai/pk/direct-functions

Implement "direct functions", which allow you to bypass specifying a …

CHANGELOG.md

@@ -9,6 +9,38 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- Added support for providing "direct" functions, which don't need an
+  accompanying `FlowsFunctionSchema` or function definition dict. Instead,
+  metadata (i.e. `name`, `description`, `properties`, and `required`) are
+  automatically extracted from a combination of the function signature and
+  docstring.
+
+  Usage:
+
+  ```python
+  # "Direct" function
+  # `params` must be the first parameter
+  async def do_something(params: FunctionCallParams, foo: int, bar: str = ""):
+    """
+    Do something interesting.
+
+    Args:
+      foo (int): The foo to do something interesting with.
+      bar (string): The bar to do something interesting with.
+    """
+
+    result = await process(foo, bar)
+    await params.result_callback({"result": result})
+
+  # ...
+
+  llm.register_direct_function(do_something)
+
+  # ...
+
+  tools = ToolsSchema(standard_tools=[do_something])
+  ```
+
 - Added `watchdog_coroutine()`. This is a watchdog helper for couroutines. So,
   if you have a coroutine that is waiting for a result and that takes a long
   time, you will need to wrap it with `watchdog_coroutine()` so the watchdog

examples/foundational/14t-function-calling-direct.py

@@ -0,0 +1,146 @@
+#
+# Copyright (c) 2025, Daily
+#
+# SPDX-License-Identifier: BSD 2-Clause License
+#
+
+import argparse
+import os
+
+from dotenv import load_dotenv
+from loguru import logger
+
+from pipecat.adapters.schemas.tools_schema import ToolsSchema
+from pipecat.audio.vad.silero import SileroVADAnalyzer
+from pipecat.frames.frames import TTSSpeakFrame
+from pipecat.pipeline.pipeline import Pipeline
+from pipecat.pipeline.runner import PipelineRunner
+from pipecat.pipeline.task import PipelineParams, PipelineTask
+from pipecat.processors.aggregators.openai_llm_context import OpenAILLMContext
+from pipecat.services.cartesia.tts import CartesiaTTSService
+from pipecat.services.deepgram.stt import DeepgramSTTService
+from pipecat.services.llm_service import FunctionCallParams
+from pipecat.services.openai.llm import OpenAILLMService
+from pipecat.transports.base_transport import BaseTransport, TransportParams
+from pipecat.transports.network.fastapi_websocket import FastAPIWebsocketParams
+from pipecat.transports.services.daily import DailyParams
+
+load_dotenv(override=True)
+
+
+async def get_current_weather(params: FunctionCallParams, location: str, format: str):
+    """
+    Get the current weather.
+
+    Args:
+        location (str): The city and state, e.g. "San Francisco, CA".
+        format (str): The temperature unit to use. Must be either "celsius" or "fahrenheit". Infer this from the user's location.
+    """
+    await params.result_callback({"conditions": "nice", "temperature": "75"})
+
+
+async def get_restaurant_recommendation(params: FunctionCallParams, location: str):
+    """
+    Get a restaurant recommendation.
+
+    Args:
+        location (str): The city and state, e.g. "San Francisco, CA".
+    """
+    await params.result_callback({"name": "The Golden Dragon"})
+
+
+# We store functions so objects (e.g. SileroVADAnalyzer) don't get
+# instantiated. The function will be called when the desired transport gets
+# selected.
+transport_params = {
+    "daily": lambda: DailyParams(
+        audio_in_enabled=True,
+        audio_out_enabled=True,
+        vad_analyzer=SileroVADAnalyzer(),
+    ),
+    "twilio": lambda: FastAPIWebsocketParams(
+        audio_in_enabled=True,
+        audio_out_enabled=True,
+        vad_analyzer=SileroVADAnalyzer(),
+    ),
+    "webrtc": lambda: TransportParams(
+        audio_in_enabled=True,
+        audio_out_enabled=True,
+        vad_analyzer=SileroVADAnalyzer(),
+    ),
+}
+
+
+async def run_example(transport: BaseTransport, _: argparse.Namespace, handle_sigint: bool):
+    logger.info(f"Starting bot")
+
+    stt = DeepgramSTTService(api_key=os.getenv("DEEPGRAM_API_KEY"))
+
+    tts = CartesiaTTSService(
+        api_key=os.getenv("CARTESIA_API_KEY"),
+        voice_id="71a7ad14-091c-4e8e-a314-022ece01c121",  # British Reading Lady
+    )
+
+    llm = OpenAILLMService(api_key=os.getenv("OPENAI_API_KEY"))
+
+    # You can also register a function_name of None to get all functions
+    # sent to the same callback with an additional function_name parameter.
+    llm.register_direct_function(get_current_weather)
+    llm.register_direct_function(get_restaurant_recommendation)
+
+    @llm.event_handler("on_function_calls_started")
+    async def on_function_calls_started(service, function_calls):
+        await tts.queue_frame(TTSSpeakFrame("Let me check on that."))
+
+    tools = ToolsSchema(standard_tools=[get_current_weather, get_restaurant_recommendation])
+
+    messages = [
+        {
+            "role": "system",
+            "content": "You are a helpful LLM in a WebRTC call. Your goal is to demonstrate your capabilities in a succinct way. Your output will be converted to audio so don't include special characters in your answers. Respond to what the user said in a creative and helpful way.",
+        },
+    ]
+
+    context = OpenAILLMContext(messages, tools)
+    context_aggregator = llm.create_context_aggregator(context)
+
+    pipeline = Pipeline(
+        [
+            transport.input(),
+            stt,
+            context_aggregator.user(),
+            llm,
+            tts,
+            transport.output(),
+            context_aggregator.assistant(),
+        ]
+    )
+
+    task = PipelineTask(
+        pipeline,
+        params=PipelineParams(
+            enable_metrics=True,
+            enable_usage_metrics=True,
+        ),
+    )
+
+    @transport.event_handler("on_client_connected")
+    async def on_client_connected(transport, client):
+        logger.info(f"Client connected")
+        # Kick off the conversation.
+        await task.queue_frames([context_aggregator.user().get_context_frame()])
+
+    @transport.event_handler("on_client_disconnected")
+    async def on_client_disconnected(transport, client):
+        logger.info(f"Client disconnected")
+        await task.cancel()
+
+    runner = PipelineRunner(handle_sigint=handle_sigint)
+
+    await runner.run(task)
+
+
+if __name__ == "__main__":
+    from pipecat.examples.run import main
+
+    main(run_example, transport_params=transport_params)

pyproject.toml

@@ -31,7 +31,8 @@ dependencies = [
     "pyloudnorm~=0.1.1",
     "resampy~=0.4.3",
     "soxr~=0.5.0",
-    "openai~=1.70.0"
+    "openai~=1.70.0",
+    "docstring_parser~=0.16"
 ]
 
 [project.urls]

src/pipecat/adapters/schemas/direct_function.py

@@ -0,0 +1,228 @@
+import inspect
+import types
+from typing import (
+    Any,
+    Callable,
+    Dict,
+    List,
+    Mapping,
+    Protocol,
+    Set,
+    Tuple,
+    Union,
+    get_args,
+    get_origin,
+    get_type_hints,
+)
+
+import docstring_parser
+
+from pipecat.adapters.schemas.function_schema import FunctionSchema
+
+
+class DirectFunction(Protocol):
+    """Protocol for a "direct" function that handles LLM function calls.
+
+    "Direct" functions' metadata is automatically extracted from their function signature and
+    docstrings, allowing them to be used without accompanying function configurations (as
+    `FunctionSchema`s or in provider-specific formats).
+    """
+
+    async def __call__(self, params: "FunctionCallParams", **kwargs: Any) -> None: ...
+
+
+class BaseDirectFunctionWrapper:
+    """
+    Base class for a wrapper around a DirectFunction that:
+    - extracts metadata from the function signature and docstring
+    - using that metadata, generates a corresponding FunctionSchema
+    """
+
+    @classmethod
+    def special_first_param_name(cls) -> str:
+        """The name of the "special" first function parameter that is ignored by the metadata
+        extraction, as it's not relevant to the LLM.
+        """
+        raise NotImplementedError("Subclasses must define the special first parameter name.")
+
+    def __init__(self, function: Callable):
+        self.__class__.validate_function(function)
+        self.function = function
+        self._initialize_metadata()
+
+    @classmethod
+    def validate_function(cls, function: Callable) -> None:
+        if not inspect.iscoroutinefunction(function):
+            raise Exception(f"Direct function {function.__name__} must be async")
+        params = list(inspect.signature(function).parameters.items())
+        special_first_param_name = cls.special_first_param_name()
+        if len(params) == 0:
+            raise Exception(
+                f"Direct function {function.__name__} must have at least one parameter ({special_first_param_name})"
+            )
+        first_param_name = params[0][0]
+        if first_param_name != special_first_param_name:
+            raise Exception(
+                f"Direct function {function.__name__} first parameter must be named '{special_first_param_name}'"
+            )
+
+    def to_function_schema(self) -> FunctionSchema:
+        return FunctionSchema(
+            name=self.name,
+            description=self.description,
+            properties=self.properties,
+            required=self.required,
+        )
+
+    def _initialize_metadata(self):
+        # Get function name
+        self.name = self.function.__name__
+
+        # Parse docstring for description and parameters
+        docstring = docstring_parser.parse(inspect.getdoc(self.function))
+
+        # Get function description
+        self.description = (docstring.description or "").strip()
+
+        # Get function parameters as JSON schemas, and the list of required parameters
+        self.properties, self.required = self._get_parameters_as_jsonschema(
+            self.function, docstring.params
+        )
+
+    # TODO: maybe to better support things like enums, check if each type is a pydantic type and use its convert-to-jsonschema function
+    def _get_parameters_as_jsonschema(
+        self, func: Callable, docstring_params: List[docstring_parser.DocstringParam]
+    ) -> Tuple[Dict[str, Any], List[str]]:
+        """
+        Get function parameters as a dictionary of JSON schemas and a list of required parameters.
+        Ignore the first parameter, as it's expected to be the "special" one.
+
+        Args:
+            func: Function to get parameters from
+            docstring_params: List of parameters extracted from the function's docstring
+
+        Returns:
+            A tuple containing:
+                - A dictionary mapping each function parameter to its JSON schema
+                - A list of required parameter names
+        """
+
+        sig = inspect.signature(func)
+        hints = get_type_hints(func)
+        properties = {}
+        required = []
+
+        for name, param in sig.parameters.items():
+            # Ignore 'self' parameter
+            if name == "self":
+                continue
+
+            # Ignore the first parameter, which is expected to be the "special" one
+            # (We have already validated that this is the case in validate_function())
+            is_first_param = name == next(iter(sig.parameters))
+            if is_first_param:
+                continue
+
+            type_hint = hints.get(name)
+
+            # Convert type hint to JSON schema
+            properties[name] = self._typehint_to_jsonschema(type_hint)
+
+            # Add whether the parameter is required
+            # If the parameter has no default value, it's required
+            if param.default is inspect.Parameter.empty:
+                required.append(name)
+
+            # Add parameter description from docstring
+            for doc_param in docstring_params:
+                if doc_param.arg_name == name:
+                    properties[name]["description"] = doc_param.description or ""
+
+        return properties, required
+
+    def _typehint_to_jsonschema(self, type_hint: Any) -> Dict[str, Any]:
+        """
+        Convert a Python type hint to a JSON Schema.
+
+        Args:
+            type_hint: A Python type hint
+
+        Returns:
+            A dictionary representing the JSON Schema
+        """
+        if type_hint is None:
+            return {}
+
+        # Handle basic types
+        if type_hint is type(None):
+            return {"type": "null"}
+        if type_hint is str:
+            return {"type": "string"}
+        elif type_hint is int:
+            return {"type": "integer"}
+        elif type_hint is float:
+            return {"type": "number"}
+        elif type_hint is bool:
+            return {"type": "boolean"}
+        elif type_hint is dict or type_hint is Dict:
+            return {"type": "object"}
+        elif type_hint is list or type_hint is List:
+            return {"type": "array"}
+
+        # Get origin and arguments for complex types
+        origin = get_origin(type_hint)
+        args = get_args(type_hint)
+
+        # Handle Optional/Union types
+        if origin is Union or origin is types.UnionType:
+            return {"anyOf": [self._typehint_to_jsonschema(arg) for arg in args]}
+
+        # Handle List, Tuple, Set with specific item types
+        if origin in (list, List, tuple, Tuple, set, Set) and args:
+            return {"type": "array", "items": self._typehint_to_jsonschema(args[0])}
+
+        # Handle Dict with specific key/value types
+        if origin in (dict, Dict) and len(args) == 2:
+            # For JSON Schema, keys must be strings
+            return {"type": "object", "additionalProperties": self._typehint_to_jsonschema(args[1])}
+
+        # Handle TypedDict
+        if hasattr(type_hint, "__annotations__"):
+            properties = {}
+            required = []
+
+            # NOTE: this does not yet support some fields being required and others not, which could happen when:
+            # - the base class is a TypedDict with required fields (total=True or not specified) and the derived class has optional fields (total=False)
+            # - Python 3.11+ NotRequired is used
+            all_fields_required = getattr(type_hint, "__total__", True)
+
+            for field_name, field_type in get_type_hints(type_hint).items():
+                properties[field_name] = self._typehint_to_jsonschema(field_type)
+                if all_fields_required:
+                    required.append(field_name)
+
+            schema = {"type": "object", "properties": properties}
+
+            if required:
+                schema["required"] = required
+
+            return schema
+
+        # Default to any type if we can't determine the specific schema
+        return {}
+
+
+class DirectFunctionWrapper(BaseDirectFunctionWrapper):
+    """
+    Wrapper around a DirectFunction that:
+    - extracts metadata from the function signature and docstring
+    - generates a corresponding FunctionSchema
+    - helps with function invocation
+    """
+
+    @classmethod
+    def special_first_param_name(cls) -> str:
+        return "params"
+
+    async def invoke(self, args: Mapping[str, Any], params: "FunctionCallParams"):
+        return await self.function(params=params, **args)

src/pipecat/adapters/schemas/tools_schema.py

@@ -13,6 +13,7 @@ and custom adapter-specific tools in the Pipecat framework.
 from enum import Enum
 from typing import Any, Dict, List, Optional
 
+from pipecat.adapters.schemas.direct_function import DirectFunction, DirectFunctionWrapper
 from pipecat.adapters.schemas.function_schema import FunctionSchema
 
 
@@ -36,7 +37,7 @@ class ToolsSchema:
 
     def __init__(
         self,
-        standard_tools: List[FunctionSchema],
+        standard_tools: List[FunctionSchema | DirectFunction],
         custom_tools: Optional[Dict[AdapterType, List[Dict[str, Any]]]] = None,
     ) -> None:
         """Initialize the tools schema.
@@ -46,7 +47,20 @@ class ToolsSchema:
             custom_tools: Dictionary mapping adapter types to their custom tool definitions.
                 These tools may not follow the FunctionSchema format (e.g., search_tool).
         """
-        self._standard_tools = standard_tools
+
+        def _map_standard_tools(tools):
+            schemas = []
+            for tool in tools:
+                if isinstance(tool, FunctionSchema):
+                    schemas.append(tool)
+                elif callable(tool):
+                    wrapper = DirectFunctionWrapper(tool)
+                    schemas.append(wrapper.to_function_schema())
+                else:
+                    raise TypeError(f"Unsupported tool type: {type(tool)}")
+            return schemas
+
+        self._standard_tools = _map_standard_tools(standard_tools)
         self._custom_tools = custom_tools
 
     @property

src/pipecat/services/llm_service.py

@@ -8,12 +8,33 @@
 
 import asyncio
 import inspect
+import types
 from dataclasses import dataclass
-from typing import Any, Awaitable, Callable, Dict, Mapping, Optional, Protocol, Sequence, Type
+from typing import (
+    Any,
+    Awaitable,
+    Callable,
+    Dict,
+    List,
+    Mapping,
+    Optional,
+    Protocol,
+    Sequence,
+    Set,
+    Tuple,
+    Type,
+    Union,
+    get_args,
+    get_origin,
+    get_type_hints,
+)
 
+import docstring_parser
 from loguru import logger
 
 from pipecat.adapters.base_llm_adapter import BaseLLMAdapter
+from pipecat.adapters.schemas.direct_function import DirectFunction, DirectFunctionWrapper
+from pipecat.adapters.schemas.function_schema import FunctionSchema
 from pipecat.adapters.services.open_ai_adapter import OpenAILLMAdapter
 from pipecat.frames.frames import (
     CancelFrame,
@@ -94,7 +115,7 @@ class FunctionCallRegistryItem:
     """
 
     function_name: Optional[str]
-    handler: FunctionCallHandler
+    handler: FunctionCallHandler | "DirectFunctionWrapper"
     cancel_on_interruption: bool
 
 
@@ -285,6 +306,19 @@ class LLMService(AIService):
 
             self._start_callbacks[function_name] = start_callback
 
+    def register_direct_function(
+        self,
+        handler: DirectFunction,
+        *,
+        cancel_on_interruption: bool = True,
+    ):
+        wrapper = DirectFunctionWrapper(handler)
+        self._functions[wrapper.name] = FunctionCallRegistryItem(
+            function_name=wrapper.name,
+            handler=wrapper,
+            cancel_on_interruption=cancel_on_interruption,
+        )
+
     def unregister_function(self, function_name: Optional[str]):
         """Remove a registered function handler.
 
@@ -295,6 +329,11 @@ class LLMService(AIService):
         if self._start_callbacks[function_name]:
             del self._start_callbacks[function_name]
 
+    def unregister_direct_function(self, handler: Any):
+        wrapper = DirectFunctionWrapper(handler)
+        del self._functions[wrapper.name]
+        # Note: no need to remove start callback here, as direct functions don't support start callbacks.
+
     def has_function(self, function_name: str):
         """Check if a function handler is registered.
 
@@ -474,35 +513,50 @@ class LLMService(AIService):
             await self.push_frame(result_frame_downstream, FrameDirection.DOWNSTREAM)
             await self.push_frame(result_frame_upstream, FrameDirection.UPSTREAM)
 
-        signature = inspect.signature(item.handler)
-        if len(signature.parameters) > 1:
-            import warnings
-
-            with warnings.catch_warnings():
-                warnings.simplefilter("always")
-                warnings.warn(
-                    "Function calls with parameters `(function_name, tool_call_id, arguments, llm, context, result_callback)` are deprecated, use a single `FunctionCallParams` parameter instead.",
-                    DeprecationWarning,
-                )
-
-            await item.handler(
-                runner_item.function_name,
-                runner_item.tool_call_id,
-                runner_item.arguments,
-                self,
-                runner_item.context,
-                function_call_result_callback,
+        if isinstance(item.handler, DirectFunctionWrapper):
+            # Handler is a DirectFunctionWrapper
+            await item.handler.invoke(
+                args=runner_item.arguments,
+                params=FunctionCallParams(
+                    function_name=runner_item.function_name,
+                    tool_call_id=runner_item.tool_call_id,
+                    arguments=runner_item.arguments,
+                    llm=self,
+                    context=runner_item.context,
+                    result_callback=function_call_result_callback,
+                ),
             )
         else:
-            params = FunctionCallParams(
-                function_name=runner_item.function_name,
-                tool_call_id=runner_item.tool_call_id,
-                arguments=runner_item.arguments,
-                llm=self,
-                context=runner_item.context,
-                result_callback=function_call_result_callback,
-            )
-            await item.handler(params)
+            # Handler is a FunctionCallHandler
+            signature = inspect.signature(item.handler)
+            if len(signature.parameters) > 1:
+                import warnings
+
+                with warnings.catch_warnings():
+                    warnings.simplefilter("always")
+                    warnings.warn(
+                        "Function calls with parameters `(function_name, tool_call_id, arguments, llm, context, result_callback)` are deprecated, use a single `FunctionCallParams` parameter instead.",
+                        DeprecationWarning,
+                    )
+
+                await item.handler(
+                    runner_item.function_name,
+                    runner_item.tool_call_id,
+                    runner_item.arguments,
+                    self,
+                    runner_item.context,
+                    function_call_result_callback,
+                )
+            else:
+                params = FunctionCallParams(
+                    function_name=runner_item.function_name,
+                    tool_call_id=runner_item.tool_call_id,
+                    arguments=runner_item.arguments,
+                    llm=self,
+                    context=runner_item.context,
+                    result_callback=function_call_result_callback,
+                )
+                await item.handler(params)
 
     async def _cancel_function_call(self, function_name: Optional[str]):
         cancelled_tasks = set()

tests/test_direct_functions.py

@@ -0,0 +1,229 @@
+import asyncio
+import unittest
+from typing import Optional, TypedDict, Union
+
+from pipecat.adapters.schemas.direct_function import DirectFunctionWrapper
+from pipecat.services.llm_service import FunctionCallParams
+
+# Copyright (c) 2025, Daily
+#
+# SPDX-License-Identifier: BSD 2-Clause License
+#
+
+
+class TestDirectFunction(unittest.TestCase):
+    def test_name_is_set_from_function(self):
+        async def my_function(params: FunctionCallParams):
+            return {"status": "success"}, None
+
+        func = DirectFunctionWrapper(function=my_function)
+        self.assertEqual(func.name, "my_function")
+
+    def test_description_is_set_from_function(self):
+        async def my_function_short_description(params: FunctionCallParams):
+            """This is a test function."""
+            return {"status": "success"}, None
+
+        func = DirectFunctionWrapper(function=my_function_short_description)
+        self.assertEqual(func.description, "This is a test function.")
+
+        async def my_function_long_description(params: FunctionCallParams):
+            """
+            This is a test function.
+
+            It does some really cool stuff.
+
+            Trust me, you'll want to use it.
+            """
+            return {"status": "success"}, None
+
+        func = DirectFunctionWrapper(function=my_function_long_description)
+        self.assertEqual(
+            func.description,
+            "This is a test function.\n\nIt does some really cool stuff.\n\nTrust me, you'll want to use it.",
+        )
+
+    def test_properties_are_set_from_function(self):
+        async def my_function_no_params(params: FunctionCallParams):
+            return {"status": "success"}, None
+
+        func = DirectFunctionWrapper(function=my_function_no_params)
+        self.assertEqual(func.properties, {})
+
+        async def my_function_simple_params(
+            params: FunctionCallParams, name: str, age: int, height: Union[float, None]
+        ):
+            return {"status": "success"}, None
+
+        func = DirectFunctionWrapper(function=my_function_simple_params)
+        self.assertEqual(
+            func.properties,
+            {
+                "name": {"type": "string"},
+                "age": {"type": "integer"},
+                "height": {"anyOf": [{"type": "number"}, {"type": "null"}]},
+            },
+        )
+
+        async def my_function_complex_params(
+            params: FunctionCallParams,
+            address_lines: list[str],
+            nickname: str | int | float,
+            extra: Optional[dict[str, str]],
+        ):
+            return {"status": "success"}, None
+
+        func = DirectFunctionWrapper(function=my_function_complex_params)
+        self.assertEqual(
+            func.properties,
+            {
+                "address_lines": {"type": "array", "items": {"type": "string"}},
+                "nickname": {
+                    "anyOf": [{"type": "string"}, {"type": "integer"}, {"type": "number"}]
+                },
+                "extra": {
+                    "anyOf": [
+                        {"type": "object", "additionalProperties": {"type": "string"}},
+                        {"type": "null"},
+                    ]
+                },
+            },
+        )
+
+        class MyInfo1(TypedDict):
+            name: str
+            age: int
+
+        class MyInfo2(TypedDict, total=False):
+            name: str
+            age: int
+
+        async def my_function_complex_type_params(
+            params: FunctionCallParams, info1: MyInfo1, info2: MyInfo2
+        ):
+            return {"status": "success"}, None
+
+        func = DirectFunctionWrapper(function=my_function_complex_type_params)
+        self.assertEqual(
+            func.properties,
+            {
+                "info1": {
+                    "type": "object",
+                    "properties": {
+                        "name": {"type": "string"},
+                        "age": {"type": "integer"},
+                    },
+                    "required": ["name", "age"],
+                },
+                "info2": {
+                    "type": "object",
+                    "properties": {
+                        "name": {"type": "string"},
+                        "age": {"type": "integer"},
+                    },
+                },
+            },
+        )
+
+    def test_required_is_set_from_function(self):
+        async def my_function_no_params(params: FunctionCallParams):
+            return {"status": "success"}, None
+
+        func = DirectFunctionWrapper(function=my_function_no_params)
+        self.assertEqual(func.required, [])
+
+        async def my_function_simple_params(
+            params: FunctionCallParams, name: str, age: int, height: Union[float, None] = None
+        ):
+            return {"status": "success"}, None
+
+        func = DirectFunctionWrapper(function=my_function_simple_params)
+        self.assertEqual(func.required, ["name", "age"])
+
+        async def my_function_complex_params(
+            params: FunctionCallParams,
+            address_lines: Optional[list[str]],
+            nickname: str | int = "Bud",
+            extra: Optional[dict[str, str]] = None,
+        ):
+            return {"status": "success"}, None
+
+        func = DirectFunctionWrapper(function=my_function_complex_params)
+        self.assertEqual(func.required, ["address_lines"])
+
+    def test_property_descriptions_are_set_from_function(self):
+        async def my_function(
+            params: FunctionCallParams, name: str, age: int, height: Union[float, None]
+        ):
+            """
+            This is a test function.
+
+            Args:
+                name (str): The name of the person.
+                age (int): The age of the person.
+                height (float | None): The height of the person in meters. Defaults to None.
+            """
+            return {"status": "success"}, None
+
+        func = DirectFunctionWrapper(function=my_function)
+
+        # Validate that the function description is still set correctly even with the longer docstring
+        self.assertEqual(func.description, "This is a test function.")
+
+        # Validate that the property descriptions are set correctly
+        self.assertEqual(
+            func.properties,
+            {
+                "name": {"type": "string", "description": "The name of the person."},
+                "age": {"type": "integer", "description": "The age of the person."},
+                "height": {
+                    "anyOf": [{"type": "number"}, {"type": "null"}],
+                    "description": "The height of the person in meters. Defaults to None.",
+                },
+            },
+        )
+
+    def test_invalid_functions_fail_validation(self):
+        def my_function_non_async(params: FunctionCallParams):
+            return {"status": "success"}, None
+
+        with self.assertRaises(Exception):
+            DirectFunctionWrapper(function=my_function_non_async)
+
+        async def my_function_missing_params():
+            return {"status": "success"}, None
+
+        with self.assertRaises(Exception):
+            DirectFunctionWrapper(my_function_missing_params)
+
+        async def my_function_misplaced_params(foo: str, params: FunctionCallParams):
+            return {"status": "success"}, None
+
+        with self.assertRaises(Exception):
+            DirectFunctionWrapper(my_function_misplaced_params)
+
+    def test_invoke_calls_function_with_args_and_params_object(self):
+        called = {}
+
+        class DummyParams:
+            pass
+
+        async def my_function(params: DummyParams, name: str, age: int):
+            called["params"] = params
+            called["name"] = name
+            called["age"] = age
+            return {"status": "success"}, None
+
+        func = DirectFunctionWrapper(function=my_function)
+        params = DummyParams()
+        args = {"name": "Alice", "age": 30}
+
+        result = asyncio.run(func.invoke(args=args, params=params))
+        self.assertEqual(result, ({"status": "success"}, None))
+        self.assertIs(called["params"], params)
+        self.assertEqual(called["name"], "Alice")
+        self.assertEqual(called["age"], 30)
+
+
+if __name__ == "__main__":
+    unittest.main()