adk-python/contributing/samples/human_in_loop/README.md
2025-05-28 16:59:52 -07:00

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# Agent with Long-Running Tools
This example demonstrates an agent using a long-running tool (`ask_for_approval`).
## Key Flow for Long-Running Tools
1. **Initial Call**: The agent calls the long-running tool (e.g., `ask_for_approval`).
2. **Initial Tool Response**: The tool immediately returns an initial response, typically indicating a "pending" status and a way to track the request (e.g., a `ticket-id`). This is sent back to the agent as a `types.FunctionResponse` (usually processed internally by the runner and then influencing the agent's next turn).
3. **Agent Acknowledges**: The agent processes this initial response and usually informs the user about the pending status.
4. **External Process/Update**: The long-running task progresses externally (e.g., a human approves the request).
5. **Crucial Step: Provide Updated Tool Response❗**:
* Once the external process completes or updates, your application **must** construct a new `types.FunctionResponse`.
* This response should use the **same `id` and `name`** as the original `FunctionCall` to the long-running tool.
* The `response` field within this `types.FunctionResponse` should contain the *updated data* (e.g., `{'status': 'approved', ...}`).
* Send this `types.FunctionResponse` back to the agent as a part within a new message using `role="user"`.
```python
# Example: After external approval
updated_tool_output_data = {
"status": "approved",
"ticket-id": ticket_id, # from original call
# ... other relevant updated data
}
updated_function_response_part = types.Part(
function_response=types.FunctionResponse(
id=long_running_function_call.id, # Original call ID
name=long_running_function_call.name, # Original call name
response=updated_tool_output_data,
)
)
# Send this back to the agent
await runner.run_async(
# ... session_id, user_id ...
new_message=types.Content(
parts=[updated_function_response_part], role="user"
),
)
```
6. **Agent Acts on Update**: The agent receives this message containing the `types.FunctionResponse` and, based on its instructions, proceeds with the next steps (e.g., calling another tool like `reimburse`).
**Why is this important?** The agent relies on receiving this subsequent `types.FunctionResponse` (provided in a message with `role="user"` containing the specific `Part`) to understand that the long-running task has concluded or its state has changed. Without it, the agent will remain unaware of the outcome of the pending task.