ADK using Vertex AI RAG

Using RAG with ADK engine, we need to setup our RAG engine corpus and tell our agent to use that as a point of reference. As you can see here RAG_CORPUS contains details of this endpoint.  

Then we use a tool called VertexAiRagRetrieval 

from google.adk.tools.retrieval.vertex_ai_rag_retrieval import (

    VertexAiRagRetrieval,

)

Then we hook it up to our agent and make these knowledge accessible 

# Initialize tools list

tools = []

# Only add RAG retrieval tool if RAG_CORPUS is configured

rag_corpus = os.environ.get("RAG_CORPUS")

if rag_corpus:

    ask_vertex_retrieval = VertexAiRagRetrieval(

        name="retrieve_rag_documentation",

        description=(

            "Use this tool to retrieve documentation and reference materials for the question from the RAG corpus,"

        ),

        rag_resources=[

            rag.RagResource(

                # please fill in your own rag corpus

                # here is a sample rag corpus for testing purpose

                # e.g. projects/123/locations/us-central1/ragCorpora/456

                rag_corpus=rag_corpus

            )

        ],

        similarity_top_k=10,

        vector_distance_threshold=0.6,

    )

    tools.append(ask_vertex_retrieval)

with using_session(session_id=uuid.uuid4()):

    root_agent = Agent(

        model="gemini-2.5-flash",

        name="ask_rag_agent",

        instruction=return_instructions_root(),

        tools=tools,

    )

from google.adk.apps import App

app = App(root_agent=root_agent, name="rag")