Skip to content

Function

FunctionTool #

Bases: AsyncBaseTool

Function Tool.

A tool that takes in a function and optionally handles workflow context.

Source code in llama-index-core/llama_index/core/tools/function_tool.py
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
class FunctionTool(AsyncBaseTool):
    """Function Tool.

    A tool that takes in a function and optionally handles workflow context.
    """

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

        # If async_fn is provided explicitly, use it. Otherwise check if fn is 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 function requires context by inspecting 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

    @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,
    ) -> "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,
        )

    @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:
        """Call."""
        if self.requires_context:
            if ctx is None:
                raise ValueError("Context is required for this tool")
            tool_output = self._fn(ctx, *args, **kwargs)
        else:
            tool_output = self._fn(*args, **kwargs)

        return ToolOutput(
            content=str(tool_output),
            tool_name=self.metadata.name,
            raw_input={"args": args, "kwargs": kwargs},
            raw_output=tool_output,
        )

    async def acall(
        self, *args: Any, ctx: Optional[Context] = None, **kwargs: Any
    ) -> ToolOutput:
        """Call."""
        if self.requires_context:
            if ctx is None:
                raise ValueError("Context is required for this tool")
            tool_output = await self._async_fn(ctx, *args, **kwargs)
        else:
            tool_output = await self._async_fn(*args, **kwargs)

        return ToolOutput(
            content=str(tool_output),
            tool_name=self.metadata.name,
            raw_input={"args": args, "kwargs": kwargs},
            raw_output=tool_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

Call.

Source code in llama-index-core/llama_index/core/tools/function_tool.py
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
def call(
    self, *args: Any, ctx: Optional[Context] = None, **kwargs: Any
) -> ToolOutput:
    """Call."""
    if self.requires_context:
        if ctx is None:
            raise ValueError("Context is required for this tool")
        tool_output = self._fn(ctx, *args, **kwargs)
    else:
        tool_output = self._fn(*args, **kwargs)

    return ToolOutput(
        content=str(tool_output),
        tool_name=self.metadata.name,
        raw_input={"args": args, "kwargs": kwargs},
        raw_output=tool_output,
    )

acall async #

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

Call.

Source code in llama-index-core/llama_index/core/tools/function_tool.py
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
async def acall(
    self, *args: Any, ctx: Optional[Context] = None, **kwargs: Any
) -> ToolOutput:
    """Call."""
    if self.requires_context:
        if ctx is None:
            raise ValueError("Context is required for this tool")
        tool_output = await self._async_fn(ctx, *args, **kwargs)
    else:
        tool_output = await self._async_fn(*args, **kwargs)

    return ToolOutput(
        content=str(tool_output),
        tool_name=self.metadata.name,
        raw_input={"args": args, "kwargs": kwargs},
        raw_output=tool_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
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
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
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
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,
    )