diff --git a/libs/vertexai/tests/integration_tests/test_callbacks.py b/libs/vertexai/tests/integration_tests/test_callbacks.py
index 3fcc343b..7a6caa48 100644
--- a/libs/vertexai/tests/integration_tests/test_callbacks.py
+++ b/libs/vertexai/tests/integration_tests/test_callbacks.py
@@ -10,7 +10,7 @@
 @pytest.mark.release
 @pytest.mark.parametrize(
     "model_name",
-    [_DEFAULT_MODEL_NAME, "text-bison@001", "code-bison@001"],
+    [_DEFAULT_MODEL_NAME, "code-bison@001"],
 )
 def test_llm_invoke(model_name: str) -> None:
     vb = VertexAICallbackHandler()
@@ -51,7 +51,7 @@ def test_chat_call(model_name: str) -> None:
 @pytest.mark.release
 @pytest.mark.parametrize(
     "model_name",
-    [_DEFAULT_MODEL_NAME, "text-bison@001", "code-bison@001"],
+    [_DEFAULT_MODEL_NAME, "code-bison@001"],
 )
 def test_invoke_config(model_name: str) -> None:
     vb = VertexAICallbackHandler()
diff --git a/libs/vertexai/tests/integration_tests/test_chat_models.py b/libs/vertexai/tests/integration_tests/test_chat_models.py
index 94890919..e58a3223 100644
--- a/libs/vertexai/tests/integration_tests/test_chat_models.py
+++ b/libs/vertexai/tests/integration_tests/test_chat_models.py
@@ -38,9 +38,9 @@
 )
 from tests.integration_tests.conftest import _DEFAULT_MODEL_NAME
 
-model_names_to_test = [None, "codechat-bison", "chat-bison", _DEFAULT_MODEL_NAME]
+model_names_to_test = ["codechat-bison", _DEFAULT_MODEL_NAME]
 
-rate_limiter = InMemoryRateLimiter(requests_per_second=0.5)
+rate_limiter = InMemoryRateLimiter(requests_per_second=1.0)
 
 
 def _check_usage_metadata(message: AIMessage) -> None:
@@ -57,20 +57,14 @@ def _check_usage_metadata(message: AIMessage) -> None:
 @pytest.mark.parametrize("model_name", model_names_to_test)
 def test_initialization(model_name: Optional[str]) -> None:
     """Test chat model initialization."""
-    if model_name:
-        model = ChatVertexAI(model_name=model_name, rate_limiter=rate_limiter)
-    else:
-        model = ChatVertexAI(rate_limiter=rate_limiter)
+    model = ChatVertexAI(model_name=model_name, rate_limiter=rate_limiter)
     assert model._llm_type == "vertexai"
 
 
 @pytest.mark.release
 @pytest.mark.parametrize("model_name", model_names_to_test)
 def test_vertexai_single_call(model_name: Optional[str]) -> None:
-    if model_name:
-        model = ChatVertexAI(model_name=model_name, rate_limiter=rate_limiter)
-    else:
-        model = ChatVertexAI(rate_limiter=rate_limiter)
+    model = ChatVertexAI(model_name=model_name, rate_limiter=rate_limiter)
     message = HumanMessage(content="Hello")
     response = model([message])
     assert isinstance(response, AIMessage)
@@ -92,10 +86,9 @@ def test_candidates() -> None:
 
 
 @pytest.mark.release
-@pytest.mark.parametrize("model_name", ["chat-bison@001", _DEFAULT_MODEL_NAME])
-async def test_vertexai_agenerate(model_name: str) -> None:
+async def test_vertexai_agenerate() -> None:
     model = ChatVertexAI(
-        temperature=0, model_name=model_name, rate_limiter=rate_limiter
+        temperature=0, model_name=_DEFAULT_MODEL_NAME, rate_limiter=rate_limiter
     )
     message = HumanMessage(content="Hello")
     response = await model.agenerate([[message]])
@@ -117,10 +110,9 @@ async def test_vertexai_agenerate(model_name: str) -> None:
 
 
 @pytest.mark.release
-@pytest.mark.parametrize("model_name", ["chat-bison@001", _DEFAULT_MODEL_NAME])
-def test_vertexai_stream(model_name: str) -> None:
+def test_vertexai_stream() -> None:
     model = ChatVertexAI(
-        temperature=0, model_name=model_name, rate_limiter=rate_limiter
+        temperature=0, model_name=_DEFAULT_MODEL_NAME, rate_limiter=rate_limiter
     )
     message = HumanMessage(content="Hello")
 
@@ -159,23 +151,6 @@ async def test_vertexai_astream() -> None:
     _check_usage_metadata(full)
 
 
-@pytest.mark.release
-def test_vertexai_single_call_with_context() -> None:
-    model = ChatVertexAI(rate_limiter=rate_limiter)
-    raw_context = (
-        "My name is Peter. You are my personal assistant. My favorite movies "
-        "are Lord of the Rings and Hobbit."
-    )
-    question = (
-        "Hello, could you recommend a good movie for me to watch this evening, please?"
-    )
-    context = SystemMessage(content=raw_context)
-    message = HumanMessage(content=question)
-    response = model([context, message])
-    assert isinstance(response, AIMessage)
-    assert isinstance(response.content, str)
-
-
 @pytest.mark.release
 def test_multimodal() -> None:
     llm = ChatVertexAI(model_name="gemini-pro-vision", rate_limiter=rate_limiter)
@@ -224,9 +199,7 @@ def test_multimodal() -> None:
 @pytest.mark.release
 @pytest.mark.parametrize("file_uri,mime_type", multimodal_inputs)
 def test_multimodal_media_file_uri(file_uri, mime_type) -> None:
-    llm = ChatVertexAI(
-        model_name="gemini-1.5-pro-preview-0514", rate_limiter=rate_limiter
-    )
+    llm = ChatVertexAI(model_name="gemini-1.5-pro-001", rate_limiter=rate_limiter)
     media_message = {
         "type": "media",
         "file_uri": file_uri,
@@ -244,9 +217,7 @@ def test_multimodal_media_file_uri(file_uri, mime_type) -> None:
 @pytest.mark.release
 @pytest.mark.parametrize("file_uri,mime_type", multimodal_inputs)
 def test_multimodal_media_inline_base64(file_uri, mime_type) -> None:
-    llm = ChatVertexAI(
-        model_name="gemini-1.5-pro-preview-0514", rate_limiter=rate_limiter
-    )
+    llm = ChatVertexAI(model_name="gemini-1.5-pro-001", rate_limiter=rate_limiter)
     storage_client = storage.Client()
     blob = storage.Blob.from_string(file_uri, client=storage_client)
     media_base64 = base64.b64encode(blob.download_as_bytes()).decode()
@@ -372,9 +343,7 @@ def test_parse_history_gemini_multimodal_FC():
 @pytest.mark.release
 @pytest.mark.parametrize("file_uri,mime_type", [video_param])
 def test_multimodal_video_metadata(file_uri, mime_type) -> None:
-    llm = ChatVertexAI(
-        model_name="gemini-1.5-pro-preview-0514", rate_limiter=rate_limiter
-    )
+    llm = ChatVertexAI(model_name="gemini-1.5-pro-001", rate_limiter=rate_limiter)
     media_message = {
         "type": "media",
         "file_uri": file_uri,
@@ -424,28 +393,10 @@ def test_multimodal_history() -> None:
     assert isinstance(response.content, str)
 
 
-@pytest.mark.release
-def test_vertexai_single_call_with_examples() -> None:
-    model = ChatVertexAI(rate_limiter=rate_limiter)
-    raw_context = "My name is Peter. You are my personal assistant."
-    question = "2+2"
-    text_question, text_answer = "4+4", "8"
-    inp = HumanMessage(content=text_question)
-    output = AIMessage(content=text_answer)
-    context = SystemMessage(content=raw_context)
-    message = HumanMessage(content=question)
-    response = model([context, message], examples=[inp, output])
-    assert isinstance(response, AIMessage)
-    assert isinstance(response.content, str)
-
-
 @pytest.mark.release
 @pytest.mark.parametrize("model_name", model_names_to_test)
 def test_vertexai_single_call_with_history(model_name: Optional[str]) -> None:
-    if model_name:
-        model = ChatVertexAI(model_name=model_name, rate_limiter=rate_limiter)
-    else:
-        model = ChatVertexAI(rate_limiter=rate_limiter)
+    model = ChatVertexAI(model_name=model_name, rate_limiter=rate_limiter)
     text_question1, text_answer1 = "How much is 2+2?", "4"
     text_question2 = "How much is 3+3?"
     message1 = HumanMessage(content=text_question1)
@@ -459,10 +410,7 @@ def test_vertexai_single_call_with_history(model_name: Optional[str]) -> None:
 @pytest.mark.release
 @pytest.mark.parametrize("model_name", ["gemini-1.0-pro-002"])
 def test_vertexai_system_message(model_name: Optional[str]) -> None:
-    if model_name:
-        model = ChatVertexAI(model_name=model_name, rate_limiter=rate_limiter)
-    else:
-        model = ChatVertexAI(rate_limiter=rate_limiter)
+    model = ChatVertexAI(model_name=model_name, rate_limiter=rate_limiter)
     system_instruction = """CymbalBank is a bank located in London"""
     text_question1 = "Where is Cymbal located? Provide only the name of the city."
     sys_message = SystemMessage(content=system_instruction)
@@ -475,14 +423,8 @@ def test_vertexai_system_message(model_name: Optional[str]) -> None:
 
 
 @pytest.mark.release
-@pytest.mark.parametrize("model_name", model_names_to_test)
-def test_vertexai_single_call_with_no_system_messages(
-    model_name: Optional[str],
-) -> None:
-    if model_name:
-        model = ChatVertexAI(model_name=model_name, rate_limiter=rate_limiter)
-    else:
-        model = ChatVertexAI(rate_limiter=rate_limiter)
+def test_vertexai_single_call_with_no_system_messages() -> None:
+    model = ChatVertexAI(model_name=_DEFAULT_MODEL_NAME, rate_limiter=rate_limiter)
     text_question1, text_answer1 = "How much is 2+2?", "4"
     text_question2 = "How much is 3+3?"
     message1 = HumanMessage(content=text_question1)
@@ -493,26 +435,12 @@ def test_vertexai_single_call_with_no_system_messages(
     assert isinstance(response.content, str)
 
 
-@pytest.mark.release
-def test_vertexai_single_call_fails_no_message() -> None:
-    chat = ChatVertexAI(rate_limiter=rate_limiter)
-    with pytest.raises(ValueError) as exc_info:
-        _ = chat([])
-    assert (
-        str(exc_info.value)
-        == "You should provide at least one message to start the chat!"
-    )
-
-
 @pytest.mark.release
 @pytest.mark.parametrize("model_name", model_names_to_test)
 def test_get_num_tokens_from_messages(model_name: str) -> None:
-    if model_name:
-        model = ChatVertexAI(
-            model_name=model_name, temperature=0.0, rate_limiter=rate_limiter
-        )
-    else:
-        model = ChatVertexAI(temperature=0.0, rate_limiter=rate_limiter)
+    model = ChatVertexAI(
+        model_name=model_name, temperature=0.0, rate_limiter=rate_limiter
+    )
     message = HumanMessage(content="Hello")
     token = model.get_num_tokens_from_messages(messages=[message])
     assert isinstance(token, int)
@@ -611,7 +539,7 @@ class MyModel(BaseModel):
         HarmCategory.HARM_CATEGORY_DANGEROUS_CONTENT: HarmBlockThreshold.BLOCK_ONLY_HIGH
     }
     model = ChatVertexAI(
-        model_name="gemini-1.5-pro-preview-0409",
+        model_name="gemini-1.5-pro-001",
         safety_settings=safety,
         rate_limiter=rate_limiter,
     ).bind(
@@ -649,9 +577,7 @@ class MyModel(BaseModel):
     safety = {
         HarmCategory.HARM_CATEGORY_DANGEROUS_CONTENT: HarmBlockThreshold.BLOCK_ONLY_HIGH
     }
-    model = ChatVertexAI(
-        model_name="gemini-1.5-pro-preview-0409", safety_settings=safety
-    ).bind(
+    model = ChatVertexAI(model_name="gemini-1.5-pro-001", safety_settings=safety).bind(
         functions=[MyModel],
         tool_config={
             "function_calling_config": {
@@ -678,7 +604,7 @@ class MyModel(BaseModel):
         HarmCategory.HARM_CATEGORY_DANGEROUS_CONTENT: HarmBlockThreshold.BLOCK_ONLY_HIGH
     }
     llm = ChatVertexAI(
-        model_name="gemini-1.5-pro-preview-0409",
+        model_name="gemini-1.5-pro-001",
         safety_settings=safety,
         rate_limiter=rate_limiter,
     )
@@ -735,7 +661,7 @@ def search(
         HarmCategory.HARM_CATEGORY_DANGEROUS_CONTENT: HarmBlockThreshold.BLOCK_ONLY_HIGH
     }
     llm = ChatVertexAI(
-        model_name="gemini-1.5-pro-preview-0409",
+        model_name="gemini-1.5-pro-001",
         safety_settings=safety,
         temperature=0,
         rate_limiter=rate_limiter,
diff --git a/libs/vertexai/tests/integration_tests/test_llms.py b/libs/vertexai/tests/integration_tests/test_llms.py
index 1be4b603..13b606e7 100644
--- a/libs/vertexai/tests/integration_tests/test_llms.py
+++ b/libs/vertexai/tests/integration_tests/test_llms.py
@@ -10,17 +10,10 @@
 from langchain_google_vertexai.llms import VertexAI
 from tests.integration_tests.conftest import _DEFAULT_MODEL_NAME
 
-model_names_to_test = [_DEFAULT_MODEL_NAME]
-model_names_to_test_with_default = [None] + model_names_to_test
-
 
 @pytest.mark.release
-@pytest.mark.parametrize(
-    "model_name",
-    model_names_to_test_with_default,
-)
-def test_vertex_initialization(model_name: str) -> None:
-    llm = VertexAI(model_name=model_name) if model_name else VertexAI()
+def test_vertex_initialization() -> None:
+    llm = VertexAI(model_name=_DEFAULT_MODEL_NAME)
     assert llm._llm_type == "vertexai"
     try:
         assert llm.model_name == llm.client._model_id
@@ -29,31 +22,15 @@ def test_vertex_initialization(model_name: str) -> None:
 
 
 @pytest.mark.release
-@pytest.mark.parametrize(
-    "model_name",
-    model_names_to_test_with_default,
-)
-def test_vertex_invoke(model_name: str) -> None:
-    llm = (
-        VertexAI(model_name=model_name, temperature=0)
-        if model_name
-        else VertexAI(temperature=0.0)
-    )
+def test_vertex_invoke() -> None:
+    llm = VertexAI(model_name=_DEFAULT_MODEL_NAME, temperature=0)
     output = llm.invoke("Say foo:")
     assert isinstance(output, str)
 
 
 @pytest.mark.release
-@pytest.mark.parametrize(
-    "model_name",
-    model_names_to_test_with_default,
-)
-def test_vertex_generate(model_name: str) -> None:
-    llm = (
-        VertexAI(model_name=model_name, temperature=0)
-        if model_name
-        else VertexAI(temperature=0.0)
-    )
+def test_vertex_generate() -> None:
+    llm = VertexAI(model_name=_DEFAULT_MODEL_NAME, temperature=0)
     output = llm.generate(["Say foo:"])
     assert isinstance(output, LLMResult)
     assert len(output.generations) == 1
@@ -87,7 +64,7 @@ def test_vertex_generate_code() -> None:
 
 @pytest.mark.release
 async def test_vertex_agenerate() -> None:
-    llm = VertexAI(temperature=0)
+    llm = VertexAI(model_name=_DEFAULT_MODEL_NAME, temperature=0)
     output = await llm.agenerate(["Please say foo:"])
     assert isinstance(output, LLMResult)
     usage_metadata = output.generations[0][0].generation_info["usage_metadata"]  # type: ignore
@@ -104,7 +81,7 @@ def test_stream() -> None:
 
 @pytest.mark.release
 async def test_vertex_consistency() -> None:
-    llm = VertexAI(temperature=0)
+    llm = VertexAI(model_name=_DEFAULT_MODEL_NAME, temperature=0)
     output = llm.generate(["Please say foo:"])
     streaming_output = llm.generate(["Please say foo:"], stream=True)
     async_output = await llm.agenerate(["Please say foo:"])
@@ -120,11 +97,7 @@ async def test_astream() -> None:
 
 
 @pytest.mark.release
-@pytest.mark.parametrize(
-    "model_name",
-    model_names_to_test,
-)
-def test_vertex_call_count_tokens(model_name: str) -> None:
-    llm = VertexAI(model_name=model_name)
+def test_vertex_call_count_tokens() -> None:
+    llm = VertexAI(model_name=_DEFAULT_MODEL_NAME)
     output = llm.get_num_tokens("How are you?")
     assert output == 4
diff --git a/libs/vertexai/tests/integration_tests/test_tools.py b/libs/vertexai/tests/integration_tests/test_tools.py
deleted file mode 100644
index 1a674931..00000000
--- a/libs/vertexai/tests/integration_tests/test_tools.py
+++ /dev/null
@@ -1,36 +0,0 @@
-from typing import List, Union
-
-from langchain_core.agents import AgentAction, AgentActionMessageLog, AgentFinish
-from langchain_core.output_parsers import BaseOutputParser
-from langchain_core.outputs import ChatGeneration, Generation
-
-
-class _TestOutputParser(BaseOutputParser):
-    def parse_result(
-        self, result: List[Generation], *, partial: bool = False
-    ) -> Union[AgentAction, AgentFinish]:
-        if not isinstance(result[0], ChatGeneration):
-            raise ValueError("This output parser only works on ChatGeneration output")
-        message = result[0].message
-        function_call = message.additional_kwargs.get("function_call", {})
-        if function_call:
-            function_name = function_call["name"]
-            tool_input = function_call.get("arguments", {})
-
-            content_msg = f"responded: {message.content}\n" if message.content else "\n"
-            log_msg = (
-                f"\nInvoking: `{function_name}` with `{tool_input}`\n{content_msg}\n"
-            )
-            return AgentActionMessageLog(
-                tool=function_name,
-                tool_input=tool_input,
-                log=log_msg,
-                message_log=[message],
-            )
-
-        return AgentFinish(
-            return_values={"output": message.content}, log=str(message.content)
-        )
-
-    def parse(self, text: str) -> Union[AgentAction, AgentFinish]:
-        raise ValueError("Can only parse messages")