Adding example for tool intercept and human approval (#252)

* Adding example for tool intercept

* Format

python/samples/tool-use/coding_one_agent_direct_intercept.py

@@ -0,0 +1,75 @@
+"""
+This example show case how to intercept the tool execution using
+intervention hanlder.
+The intervention handler is used to intercept the FunctionCall message
+before it is sent out, and prompt the user for permission to execute the tool.
+"""
+
+import asyncio
+import os
+import sys
+from typing import Any, List
+
+from agnext.application import SingleThreadedAgentRuntime
+from agnext.components import FunctionCall
+from agnext.components.code_executor import LocalCommandLineCodeExecutor
+from agnext.components.models import SystemMessage
+from agnext.components.tools import PythonCodeExecutionTool, Tool
+from agnext.core import AgentId
+from agnext.core.intervention import DefaultInterventionHandler, DropMessage
+
+sys.path.append(os.path.abspath(os.path.join(os.path.dirname(__file__), "..")))
+
+from coding_one_agent_direct import FunctionExecutionException, Message, ToolEnabledAgent
+from common.utils import get_chat_completion_client_from_envs
+
+
+class ToolInterventionHandler(DefaultInterventionHandler):
+    async def on_send(self, message: Any, *, sender: AgentId | None, recipient: AgentId) -> Any | type[DropMessage]:
+        if isinstance(message, FunctionCall):
+            # Request user prompt for tool execution.
+            user_input = input(
+                f"Function call: {message.name}\nArguments: {message.arguments}\nDo you want to execute the tool? (y/n): "
+            )
+            if user_input.strip().lower() != "y":
+                raise FunctionExecutionException(content="User denied tool execution.", call_id=message.id)
+        return message
+
+
+async def main() -> None:
+    # Create the runtime with the intervention handler.
+    runtime = SingleThreadedAgentRuntime(intervention_handler=ToolInterventionHandler())
+    # Define the tools.
+    tools: List[Tool] = [
+        # A tool that executes Python code.
+        PythonCodeExecutionTool(
+            LocalCommandLineCodeExecutor(),
+        )
+    ]
+    # Register agents.
+    tool_agent = await runtime.register_and_get(
+        "tool_enabled_agent",
+        lambda: ToolEnabledAgent(
+            description="Tool Use Agent",
+            system_messages=[SystemMessage("You are a helpful AI Assistant. Use your tools to solve problems.")],
+            model_client=get_chat_completion_client_from_envs(model="gpt-3.5-turbo"),
+            tools=tools,
+        ),
+    )
+
+    run_context = runtime.start()
+
+    # Send a task to the tool user.
+    response = await runtime.send_message(Message("Run the following Python code: print('Hello, World!')"), tool_agent)
+    print(response.content)
+
+    # Run the runtime until the task is completed.
+    await run_context.stop()
+
+
+if __name__ == "__main__":
+    import logging
+
+    logging.basicConfig(level=logging.WARNING)
+    logging.getLogger("agnext").setLevel(logging.DEBUG)
+    asyncio.run(main())