VertexAISearchTool is not accessible

[naitik-parekh]

I have created the following agent hierarchy using ADK 1.13.0.

The code snippets of agents definition are as follows:

agent_2 = Agent()
agent_3 = Agent()
agent_4 = Agent()

agent_1 = Agent(
    sub_agents = [agent_2, agent_3, agent_4]
)

agent_6 = Agent(
    tools = [VertexAiSearchTool()]
)

agent_5 = Agent(
    tools = [AgentTool(agent=agent_6, skip_summarization=True)]
)

agent_7 = Agent(
    tools=[VertexAiSearchTool()]
)

root_agent = Agent(
    sub_agents=[
        agent_1,
        agent_5,
    ],
    tools=[
        AgentTool(agent=agent_7, skip_summarization=True)
    ],
)

The VertexAiSearchTool under agent_6 is not working. The agent_6 replies that tool is not found or not accessible.

I am familiar with the limitation that "Built-in tools cannot be used within a sub-agent". In the agent hierarchy I have created, is the VertexAiSearchTool under agent_6 not working due to this limitation? I have used AgentTool for agent_6 to mitigate the limitation. But is it the case that as agent_5 is a sub-agent, any configuration under it cannot use built-in tools?

[naitik-parekh]

I have initialized VertexAiSearchTool with data_store_id. For this configuration I do not think there is a need to map the data store to a search app. Correct me if I am wrong.

Apparently, after creating a new search app in the AI Applications Console and linking it to the data store used by agent_6's VertexAiSearchTool, the agent has been intermittently retrieving responses from the data store. On several occasions, agent_6 returns an LLM response such as, “The tool I need to use ............ is not working right now".

Is there a need to have the data store connected to any search app for it to be used in VertexAiSearchTool?

When the LLM response says that tool is not working, I do not see any errors/failures in the ADK debug logs. Is this expected behaviour? What can be checked further to find the issue?

[adk-bot]

Response from ADK Answering Agent (experimental, answer may be inaccurate)

TLDR: Your analysis is correct. The VertexAiSearchTool is failing due to a known limitation in ADK where built-in tools cannot be used within a sub-agent's hierarchy. Your agent_6 is nested under agent_5, which is a sub-agent, thus causing the issue.

---

Hello! Thanks for your detailed question.

Your understanding is spot on. The problem you're encountering with VertexAiSearchTool in agent_6 is indeed due to the ADK limitation that built-in tools cannot be used within a sub-agent. [1]

Let's break down your agent hierarchy:

1. root_agent is your top-level agent.
2. agent_5 is defined as a sub_agent within root_agent.
3. agent_6, which contains the VertexAiSearchTool, is used as a tool by agent_5.

Because agent_5 is a sub-agent, this restriction applies to it and any agents used as tools underneath it, like agent_6. Using AgentTool to wrap agent_6 is the correct approach for making an agent act as a tool, but it does not bypass this specific sub-agent limitation.

Your implementation of agent_7 is the correct and recommended pattern for using an agent with a built-in tool: it is added to the tools list of the root_agent (which is not a sub-agent). This works as expected.

To resolve this, you would need to restructure your hierarchy so that the agent using VertexAiSearchTool is not nested under a sub-agent. For instance, you could make the agent containing the search functionality parallel to agent_7 and add it directly to the root_agent's tools list.

[1] https://google.github.io/adk-docs/tools/built-in-tools/

[naitik-parekh]

Thank you for clarification.

Your explanation does not match my observation. As mentioned in my previous comment, the vertexAiSearchTool (with agent_6) is working intermittently after connecting the corresponding data store with a search app.

In my initial attempts, the vertexAiSearchTool (with agent_6) was not working at all. After some debugging I have found out that the data store I had created with structured data was not indexed implicitly after creation. On connecting the data store to a search app, the documents are indexed. After that, the vertexAISearchTool (with agent_6) is working intermittently.

To me it appears to be some issue around using a data store with structured data.

PS.
The vertexAiSearchTool (with agent_7) used data store with unstructured data. This is working smoothly and the documents are also indexed automatically without connect the data store to search app.