Built-in tools

The Koog framework provides built-in tools that handle common scenarios of agent-user interaction.

The following built-in tools are available:

Tool	Name	Description
SayToUser	__say_to_user__	Lets the agent send a message to the user. It prints the agent message to the console with the Agent says: prefix.
AskUser	__ask_user__	Lets the agent ask the user for input. It prints the agent message to the console and waits for user response.
ExitTool	__exit__	Lets the agent finish the conversation and terminate the session.
ReadFileTool	__read_file__	Reads text file with optional line range selection. Returns formatted content with metadata using 0-based line indexing.
EditFileTool	__edit_file__	Makes a single, targeted text replacement in a file; can also create new files or fully replace contents.
ListDirectoryTool	__list_directory__	Lists directory contents as a hierarchical tree with optional depth control and glob filtering.
WriteFileTool	__write_file__	Writes text content to a file (creating parent directories if needed).

Registering built-in tools

Like any other tool, a built-in tool must be added to the tool registry to become available for an agent. Here is an example:

// Create a tool registry with all built-in tools
val toolRegistry = ToolRegistry {
    tool(SayToUser)
    tool(AskUser)
    tool(ExitTool)
    tool(ReadFileTool(JVMFileSystemProvider.ReadOnly))
    tool(ListDirectoryTool(JVMFileSystemProvider.ReadOnly))
    tool(WriteFileTool(JVMFileSystemProvider.ReadWrite))
}

// Pass the registry when creating an agent
val agent = AIAgent(
    promptExecutor = simpleOpenAIExecutor(apiToken),
    systemPrompt = "You are a helpful assistant.",
    llmModel = OpenAIModels.Chat.GPT4o,
    toolRegistry = toolRegistry
)

You can create a comprehensive set of capabilities for your agent by combining built-in tools and custom tools within the same registry. To learn more about custom tools, see Annotation-based tools and Class-based tools.