Reverse invoking a Tool means that a plugin can call other tool-type plugins within the Dify platform. If you are unfamiliar with the basic concepts of reverse invocation, please first read Reverse Invocation of Dify Services.

Consider the following scenarios:

  • A tool-type plugin has implemented a function, but the result is not as expected, requiring post-processing of the data.
  • A task requires a web scraper, and you want the flexibility to choose the scraping service.
  • You need to aggregate results from multiple tools, but it’s difficult to handle using a Workflow application.

In these cases, you need to call other existing tools within your plugin. These tools might be from the marketplace, a self-built Workflow as a Tool, or a custom tool.

These requirements can be met by calling the self.session.tool field of the plugin.

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Calling Installed Tools

Allows the plugin to call various tools installed in the current Workspace, including other tool-type plugins.

Entry Point

    self.session.tool

Interface

    def invoke_builtin_tool(
        self, provider: str, tool_name: str, parameters: dict[str, Any]
    ) -> Generator[ToolInvokeMessage, None, None]:
        pass

Here, provider is the plugin ID plus the tool provider name, formatted like langgenius/google/google. tool_name is the specific tool name, and parameters are the arguments passed to the tool.

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Calling Workflow as Tool

For more information on Workflow as Tool, please refer to the Tool Plugin documentation. (Note: Original link /plugin-dev-zh/9223-tool does not exist in English list, linked to closest match).

Entry Point

    self.session.tool

Interface

    def invoke_workflow_tool(
        self, provider: str, tool_name: str, parameters: dict[str, Any]
    ) -> Generator[ToolInvokeMessage, None, None]:
        pass

In this case, provider is the ID of this tool, and tool_name is specified during the creation of the tool.

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Calling Custom Tool

Entry Point

    self.session.tool

Interface

    def invoke_api_tool(
        self, provider: str, tool_name: str, parameters: dict[str, Any]
    ) -> Generator[ToolInvokeMessage, None, None]:
        pass

Here, provider is the ID of this tool, and tool_name is the operation_id from the OpenAPI specification. If it doesn’t exist, it’s the tool_name automatically generated by Dify, which can be found on the tool management page.

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