eino-examples/flow/agent/react/unknown_tool_handler_example

Unknown Tools Handler for ReAct Agent

• Demonstrates UnknownToolsHandler in compose.ToolsNodeConfig when the model emits an unknown tool call.
• Mock ChatModel produces three turns: unknown tool call → correct tool call → final answer.
• Builds on the ReAct agent from the flow package.

Rationale

• ReAct agents often rely on the model to select tool names from a provided list. In practice, models may hallucinate a tool name not registered with the ToolsNode.
• Instead of aborting the agent on such an error, the UnknownToolsHandler produces a clear, structured message that is fed back to the ChatModel as the tool result.
• This feedback informs the model that the tool name is invalid and encourages it to pick a valid tool in the next turn, improving robustness and convergence.
• The example shows: first turn emits an unknown tool call; the handler returns guidance; the second turn uses the correct tool; the final turn produces the answer.

Run

• cd flow/agent/react/unknown_tool_handler_example
• go run main.go

Expected

• Prints a handler message for the unknown tool name.
• Executes the sum tool on the second turn and returns {"sum":3}.
• Outputs the final assistant answer 3.