Subagent Agent Transfers to Parent Agent

[sertacakdogan]

Describe the bug
Eventhough I'm directing subagents to transfer_to_agent to parent agent after the operation finish, it does not comply my rules.
(I'm not using Agent Tool because using subagent is more suitable for my use case)

To Reproduce
Instruct subagent to return back to the parent agent and run the root agent in a way that uses subagent.
It sometimes comply sometimes does not comply.

Expected behavior
It should have turn back to the parent agent.

Desktop (please complete the following information):

• OS: [e.g. macOS, Linux, Windows]: Mac
• Python version(python -V): 3.13
• ADK version(pip show google-adk): 1.1.20

Model Information:

• Are you using LiteLLM: Yes and No (both does not work)
• Which model is being used: gemini-2.5-flash

Additional context
I've a recommendation, intruducing a parameter specifically for this task, eable subagents to return back to the parent.
It can be an ADK parameter on agent which is boolean.

[lazharichir]

If #2253 gets merged, it should help.

[pretbc]

is this could be a part of RemoteA2aAgent ?

[sertacakdogan]

For the consideration of the development team.

After the issue I used a stronger model via LiteLLM (antrophic/claud-haiku-4.5.). This might be related to model capability.

[llalitkumarrr]

Hello @sertacakdogan ,

LLMAgents typically decide dynamically how to proceed based on the model’s response and the instructions you provide naturally play a major role in guiding that behavior.

However if you are looking for more controlled or deterministic execution, we recommend exploring workflow agents. You can choose the type of workflow agent that best fits your requirements.

[adk-bot]

This issue has been automatically marked as stale because it has not had recent activity for 7 days after a maintainer requested clarification. It will be closed if no further activity occurs within 7 days.