diff --git a/python/flink_agents/e2e_tests/e2e_tests_integration/chat_model_integration_test.py b/python/flink_agents/e2e_tests/e2e_tests_integration/chat_model_integration_test.py
index 07bae38e9..ddebe7d80 100644
--- a/python/flink_agents/e2e_tests/e2e_tests_integration/chat_model_integration_test.py
+++ b/python/flink_agents/e2e_tests/e2e_tests_integration/chat_model_integration_test.py
@@ -29,17 +29,12 @@
 current_dir = Path(__file__).parent
 
 TONGYI_MODEL = os.environ.get("TONGYI_CHAT_MODEL", "qwen-plus")
-os.environ["TONGYI_CHAT_MODEL"] = TONGYI_MODEL
 OLLAMA_MODEL = os.environ.get("OLLAMA_CHAT_MODEL", "qwen3:1.7b")
-os.environ["OLLAMA_CHAT_MODEL"] = OLLAMA_MODEL
 OPENAI_MODEL = os.environ.get("OPENAI_CHAT_MODEL", "gpt-3.5-turbo")
-os.environ["OPENAI_CHAT_MODEL"] = OPENAI_MODEL
 AZURE_OPENAI_MODEL = os.environ.get("AZURE_OPENAI_CHAT_MODEL", "gpt-5")
-os.environ["AZURE_OPENAI_CHAT_MODEL"] = AZURE_OPENAI_MODEL
 AZURE_OPENAI_API_VERSION = os.environ.get(
     "AZURE_OPENAI_API_VERSION", "2025-04-01-preview"
 )
-os.environ["AZURE_OPENAI_API_VERSION"] = AZURE_OPENAI_API_VERSION
 
 DASHSCOPE_API_KEY = os.environ.get("DASHSCOPE_API_KEY")
 OPENAI_API_KEY = os.environ.get("OPENAI_API_KEY")
@@ -78,8 +73,15 @@
         ),
     ],
 )
-def test_chat_model_integration(model_provider: str) -> None:
-    os.environ["MODEL_PROVIDER"] = model_provider
+def test_chat_model_integration(
+    model_provider: str, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    monkeypatch.setenv("TONGYI_CHAT_MODEL", TONGYI_MODEL)
+    monkeypatch.setenv("OLLAMA_CHAT_MODEL", OLLAMA_MODEL)
+    monkeypatch.setenv("OPENAI_CHAT_MODEL", OPENAI_MODEL)
+    monkeypatch.setenv("AZURE_OPENAI_CHAT_MODEL", AZURE_OPENAI_MODEL)
+    monkeypatch.setenv("AZURE_OPENAI_API_VERSION", AZURE_OPENAI_API_VERSION)
+    monkeypatch.setenv("MODEL_PROVIDER", model_provider)
     env = AgentsExecutionEnvironment.get_execution_environment()
     input_list = []
     agent = ChatModelTestAgent()
diff --git a/python/flink_agents/e2e_tests/e2e_tests_integration/react_agent_test.py b/python/flink_agents/e2e_tests/e2e_tests_integration/react_agent_test.py
index 85cd42bfd..04d0be41d 100644
--- a/python/flink_agents/e2e_tests/e2e_tests_integration/react_agent_test.py
+++ b/python/flink_agents/e2e_tests/e2e_tests_integration/react_agent_test.py
@@ -51,7 +51,6 @@
 os.environ["PYTHONPATH"] = sysconfig.get_paths()["purelib"]
 
 OLLAMA_MODEL = os.environ.get("REACT_OLLAMA_MODEL", "qwen3:1.7b")
-os.environ["OLLAMA_CHAT_MODEL"] = OLLAMA_MODEL
 
 
 class InputData(BaseModel):
@@ -78,7 +77,8 @@ def get_key(self, value: Row) -> int:
 @pytest.mark.skipif(
     client is None, reason="Ollama client is not available or test model is missing"
 )
-def test_react_agent_on_local_runner() -> None:
+def test_react_agent_on_local_runner(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setenv("OLLAMA_CHAT_MODEL", OLLAMA_MODEL)
     env = AgentsExecutionEnvironment.get_execution_environment()
     env.get_config().set(
         AgentExecutionOptions.ERROR_HANDLING_STRATEGY, ErrorHandlingStrategy.RETRY
@@ -138,7 +138,10 @@ def test_react_agent_on_local_runner() -> None:
 @pytest.mark.skipif(
     client is None, reason="Ollama client is not available or test model is missing"
 )
-def test_react_agent_on_remote_runner(tmp_path: Path) -> None:
+def test_react_agent_on_remote_runner(
+    tmp_path: Path, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    monkeypatch.setenv("OLLAMA_CHAT_MODEL", OLLAMA_MODEL)
     stream_env = StreamExecutionEnvironment.get_execution_environment()
 
     stream_env.set_parallelism(1)
diff --git a/python/flink_agents/e2e_tests/e2e_tests_resource_cross_language/chat_model_cross_language_test.py b/python/flink_agents/e2e_tests/e2e_tests_resource_cross_language/chat_model_cross_language_test.py
index 42a5dd719..c17110954 100644
--- a/python/flink_agents/e2e_tests/e2e_tests_resource_cross_language/chat_model_cross_language_test.py
+++ b/python/flink_agents/e2e_tests/e2e_tests_resource_cross_language/chat_model_cross_language_test.py
@@ -41,7 +41,6 @@
 current_dir = Path(__file__).parent
 
 OLLAMA_MODEL = os.environ.get("OLLAMA_CHAT_MODEL", "qwen3:1.7b")
-os.environ["OLLAMA_CHAT_MODEL"] = OLLAMA_MODEL
 
 client = pull_model(OLLAMA_MODEL)
 
@@ -51,7 +50,10 @@
 @pytest.mark.skipif(
     client is None, reason="Ollama client is not available or test model is missing."
 )
-def test_java_chat_model_integration(tmp_path: Path) -> None:
+def test_java_chat_model_integration(
+    tmp_path: Path, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    monkeypatch.setenv("OLLAMA_CHAT_MODEL", OLLAMA_MODEL)
     env = StreamExecutionEnvironment.get_execution_environment()
     env.set_runtime_mode(RuntimeExecutionMode.STREAMING)
     env.set_parallelism(1)
diff --git a/python/flink_agents/e2e_tests/e2e_tests_resource_cross_language/yaml_cross_language_test.py b/python/flink_agents/e2e_tests/e2e_tests_resource_cross_language/yaml_cross_language_test.py
index ae9920f4e..442c729eb 100644
--- a/python/flink_agents/e2e_tests/e2e_tests_resource_cross_language/yaml_cross_language_test.py
+++ b/python/flink_agents/e2e_tests/e2e_tests_resource_cross_language/yaml_cross_language_test.py
@@ -69,7 +69,6 @@
 os.environ["PYTHONPATH"] = sysconfig.get_paths()["purelib"]
 
 OLLAMA_MODEL = os.environ.get("OLLAMA_CHAT_MODEL", "qwen3:1.7b")
-os.environ["OLLAMA_CHAT_MODEL"] = OLLAMA_MODEL
 
 _client = pull_model(OLLAMA_MODEL)
 
@@ -86,13 +85,16 @@
         "flink-agents-end-to-end-tests-resource-cross-language' first."
     ),
 )
-def test_yaml_cross_language_agent(tmp_path: Path) -> None:
+def test_yaml_cross_language_agent(
+    tmp_path: Path, monkeypatch: pytest.MonkeyPatch
+) -> None:
     """``load_yaml`` → ``apply(by name)`` with a YAML-declared Java tool.
 
     Exercises a Python Ollama chat model that calls a Java
     ``calculateBMI`` tool declared in YAML and resolved against the
     cross-language test JAR.
     """
+    monkeypatch.setenv("OLLAMA_CHAT_MODEL", OLLAMA_MODEL)
     config = Configuration()
     config.set_string("python.pythonpath", sysconfig.get_paths()["purelib"])
     env = StreamExecutionEnvironment.get_execution_environment(config)