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Function

FunctionTool #

Bases: AsyncBaseTool

Function Tool.

A tool that takes in a function, optionally handles workflow context, and allows the use of callbacks. The callback can return a new ToolOutput to override the default one or a string that will be used as the final content.

Source code in llama-index-core/llama_index/core/tools/function_tool.py
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class FunctionTool(AsyncBaseTool):
    """Function Tool.

    A tool that takes in a function, optionally handles workflow context,
    and allows the use of callbacks. The callback can return a new ToolOutput
    to override the default one or a string that will be used as the final content.
    """

    def __init__(
        self,
        fn: Optional[Callable[..., Any]] = None,
        metadata: Optional[ToolMetadata] = None,
        async_fn: Optional[Callable[..., Any]] = None,
        callback: Optional[Callable[..., Any]] = None,
        async_callback: Optional[Callable[..., Any]] = None,
    ) -> None:
        if fn is None and async_fn is None:
            raise ValueError("fn or async_fn must be provided.")

        # Handle function (sync and async)
        if async_fn is not None:
            self._async_fn = async_fn
            self._fn = fn or async_to_sync(async_fn)
        else:
            assert fn is not None
            if inspect.iscoroutinefunction(fn):
                self._async_fn = fn
                self._fn = async_to_sync(fn)
            else:
                self._fn = fn
                self._async_fn = sync_to_async(fn)

        # Determine if the function requires context by inspecting its signature
        fn_to_inspect = fn or async_fn
        assert fn_to_inspect is not None
        sig = inspect.signature(fn_to_inspect)
        self.requires_context = any(
            param.annotation == Context for param in sig.parameters.values()
        )

        if metadata is None:
            raise ValueError("metadata must be provided")
        self._metadata = metadata

        # Handle callback (sync and async)
        self._callback = None
        if callback is not None:
            self._callback = callback
        elif async_callback is not None:
            self._callback = async_to_sync(async_callback)

        self._async_callback = None
        if async_callback is not None:
            self._async_callback = async_callback
        elif self._callback is not None:
            self._async_callback = sync_to_async(self._callback)

    def _run_sync_callback(self, result: Any) -> CallbackReturn:
        """Runs the sync callback, if provided, and returns either a ToolOutput
        to override the default output or a string to override the content.
        """
        if self._callback:
            ret: CallbackReturn = self._callback(result)
            return ret
        return None

    async def _run_async_callback(self, result: Any) -> CallbackReturn:
        """Runs the async callback, if provided, and returns either a ToolOutput
        to override the default output or a string to override the content.
        """
        if self._async_callback:
            ret: CallbackReturn = await self._async_callback(result)
            return ret
        return None

    @classmethod
    def from_defaults(
        cls,
        fn: Optional[Callable[..., Any]] = None,
        name: Optional[str] = None,
        description: Optional[str] = None,
        return_direct: bool = False,
        fn_schema: Optional[Type[BaseModel]] = None,
        async_fn: Optional[AsyncCallable] = None,
        tool_metadata: Optional[ToolMetadata] = None,
        callback: Optional[Callable[[Any], Any]] = None,
        async_callback: Optional[AsyncCallable] = None,
    ) -> "FunctionTool":
        if tool_metadata is None:
            fn_to_parse = fn or async_fn
            assert fn_to_parse is not None, "fn must be provided"
            name = name or fn_to_parse.__name__
            docstring = fn_to_parse.__doc__

            # Get function signature
            fn_sig = inspect.signature(fn_to_parse)

            # Remove ctx parameter from schema if present
            has_ctx = any(
                param.annotation == Context for param in fn_sig.parameters.values()
            )
            ctx_param_name = None
            if has_ctx:
                ctx_param_name = next(
                    param.name
                    for param in fn_sig.parameters.values()
                    if param.annotation == Context
                )
                fn_sig = fn_sig.replace(
                    parameters=[
                        param
                        for param in fn_sig.parameters.values()
                        if param.annotation != Context
                    ]
                )

            # Handle FieldInfo defaults
            fn_sig = fn_sig.replace(
                parameters=[
                    param.replace(default=inspect.Parameter.empty)
                    if isinstance(param.default, FieldInfo)
                    else param
                    for param in fn_sig.parameters.values()
                ]
            )

            description = description or f"{name}{fn_sig}\n{docstring}"
            if fn_schema is None:
                fn_schema = create_schema_from_function(
                    f"{name}",
                    fn_to_parse,
                    additional_fields=None,
                    ignore_fields=[ctx_param_name]
                    if ctx_param_name is not None
                    else None,
                )
            tool_metadata = ToolMetadata(
                name=name,
                description=description,
                fn_schema=fn_schema,
                return_direct=return_direct,
            )
        return cls(
            fn=fn,
            metadata=tool_metadata,
            async_fn=async_fn,
            callback=callback,
            async_callback=async_callback,
        )

    @property
    def metadata(self) -> ToolMetadata:
        """Metadata."""
        return self._metadata

    @property
    def fn(self) -> Callable[..., Any]:
        """Function."""
        return self._fn

    @property
    def async_fn(self) -> AsyncCallable:
        """Async function."""
        return self._async_fn

    def call(
        self, *args: Any, ctx: Optional[Context] = None, **kwargs: Any
    ) -> ToolOutput:
        """Sync Call."""
        if self.requires_context:
            if ctx is None:
                raise ValueError("Context is required for this tool")
            raw_output = self._fn(ctx, *args, **kwargs)
        else:
            raw_output = self._fn(*args, **kwargs)
        # Default ToolOutput based on the raw output
        default_output = ToolOutput(
            content=str(raw_output),
            tool_name=self.metadata.name,
            raw_input={"args": args, "kwargs": kwargs},
            raw_output=raw_output,
        )
        # Check for a sync callback override
        callback_result = self._run_sync_callback(raw_output)
        if callback_result is not None:
            if isinstance(callback_result, ToolOutput):
                return callback_result
            else:
                # Assume callback_result is a string to override the content.
                return ToolOutput(
                    content=str(callback_result),
                    tool_name=self.metadata.name,
                    raw_input={"args": args, "kwargs": kwargs},
                    raw_output=raw_output,
                )
        return default_output

    async def acall(
        self, *args: Any, ctx: Optional[Context] = None, **kwargs: Any
    ) -> ToolOutput:
        """Async Call."""
        if self.requires_context:
            if ctx is None:
                raise ValueError("Context is required for this tool")
            raw_output = await self._async_fn(ctx, *args, **kwargs)
        else:
            raw_output = await self._async_fn(*args, **kwargs)
        # Default ToolOutput based on the raw output
        default_output = ToolOutput(
            content=str(raw_output),
            tool_name=self.metadata.name,
            raw_input={"args": args, "kwargs": kwargs},
            raw_output=raw_output,
        )
        # Check for an async callback override
        callback_result = await self._run_async_callback(raw_output)
        if callback_result is not None:
            if isinstance(callback_result, ToolOutput):
                return callback_result
            else:
                # Assume callback_result is a string to override the content.
                return ToolOutput(
                    content=str(callback_result),
                    tool_name=self.metadata.name,
                    raw_input={"args": args, "kwargs": kwargs},
                    raw_output=raw_output,
                )
        return default_output

    def to_langchain_tool(self, **langchain_tool_kwargs: Any) -> "Tool":
        """To langchain tool."""
        from llama_index.core.bridge.langchain import Tool

        langchain_tool_kwargs = self._process_langchain_tool_kwargs(
            langchain_tool_kwargs
        )
        return Tool.from_function(
            func=self.fn,
            coroutine=self.async_fn,
            **langchain_tool_kwargs,
        )

    def to_langchain_structured_tool(
        self, **langchain_tool_kwargs: Any
    ) -> "StructuredTool":
        """To langchain structured tool."""
        from llama_index.core.bridge.langchain import StructuredTool

        langchain_tool_kwargs = self._process_langchain_tool_kwargs(
            langchain_tool_kwargs
        )
        return StructuredTool.from_function(
            func=self.fn,
            coroutine=self.async_fn,
            **langchain_tool_kwargs,
        )

metadata property #

metadata: ToolMetadata

Metadata.

fn property #

fn: Callable[..., Any]

Function.

async_fn property #

async_fn: AsyncCallable

Async function.

call #

call(*args: Any, ctx: Optional[Context] = None, **kwargs: Any) -> ToolOutput

Sync Call.

Source code in llama-index-core/llama_index/core/tools/function_tool.py
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def call(
    self, *args: Any, ctx: Optional[Context] = None, **kwargs: Any
) -> ToolOutput:
    """Sync Call."""
    if self.requires_context:
        if ctx is None:
            raise ValueError("Context is required for this tool")
        raw_output = self._fn(ctx, *args, **kwargs)
    else:
        raw_output = self._fn(*args, **kwargs)
    # Default ToolOutput based on the raw output
    default_output = ToolOutput(
        content=str(raw_output),
        tool_name=self.metadata.name,
        raw_input={"args": args, "kwargs": kwargs},
        raw_output=raw_output,
    )
    # Check for a sync callback override
    callback_result = self._run_sync_callback(raw_output)
    if callback_result is not None:
        if isinstance(callback_result, ToolOutput):
            return callback_result
        else:
            # Assume callback_result is a string to override the content.
            return ToolOutput(
                content=str(callback_result),
                tool_name=self.metadata.name,
                raw_input={"args": args, "kwargs": kwargs},
                raw_output=raw_output,
            )
    return default_output

acall async #

acall(*args: Any, ctx: Optional[Context] = None, **kwargs: Any) -> ToolOutput

Async Call.

Source code in llama-index-core/llama_index/core/tools/function_tool.py
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async def acall(
    self, *args: Any, ctx: Optional[Context] = None, **kwargs: Any
) -> ToolOutput:
    """Async Call."""
    if self.requires_context:
        if ctx is None:
            raise ValueError("Context is required for this tool")
        raw_output = await self._async_fn(ctx, *args, **kwargs)
    else:
        raw_output = await self._async_fn(*args, **kwargs)
    # Default ToolOutput based on the raw output
    default_output = ToolOutput(
        content=str(raw_output),
        tool_name=self.metadata.name,
        raw_input={"args": args, "kwargs": kwargs},
        raw_output=raw_output,
    )
    # Check for an async callback override
    callback_result = await self._run_async_callback(raw_output)
    if callback_result is not None:
        if isinstance(callback_result, ToolOutput):
            return callback_result
        else:
            # Assume callback_result is a string to override the content.
            return ToolOutput(
                content=str(callback_result),
                tool_name=self.metadata.name,
                raw_input={"args": args, "kwargs": kwargs},
                raw_output=raw_output,
            )
    return default_output

to_langchain_tool #

to_langchain_tool(**langchain_tool_kwargs: Any) -> Tool

To langchain tool.

Source code in llama-index-core/llama_index/core/tools/function_tool.py
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def to_langchain_tool(self, **langchain_tool_kwargs: Any) -> "Tool":
    """To langchain tool."""
    from llama_index.core.bridge.langchain import Tool

    langchain_tool_kwargs = self._process_langchain_tool_kwargs(
        langchain_tool_kwargs
    )
    return Tool.from_function(
        func=self.fn,
        coroutine=self.async_fn,
        **langchain_tool_kwargs,
    )

to_langchain_structured_tool #

to_langchain_structured_tool(**langchain_tool_kwargs: Any) -> StructuredTool

To langchain structured tool.

Source code in llama-index-core/llama_index/core/tools/function_tool.py
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def to_langchain_structured_tool(
    self, **langchain_tool_kwargs: Any
) -> "StructuredTool":
    """To langchain structured tool."""
    from llama_index.core.bridge.langchain import StructuredTool

    langchain_tool_kwargs = self._process_langchain_tool_kwargs(
        langchain_tool_kwargs
    )
    return StructuredTool.from_function(
        func=self.fn,
        coroutine=self.async_fn,
        **langchain_tool_kwargs,
    )