diff --git a/litellm/llms/a2a/chat/transformation.py b/litellm/llms/a2a/chat/transformation.py
index 3de584d1d5f..778f6c5324e 100644
--- a/litellm/llms/a2a/chat/transformation.py
+++ b/litellm/llms/a2a/chat/transformation.py
@@ -91,12 +91,16 @@ class A2AConfig(BaseConfig):
         return api_base, api_key, headers
 
     def get_supported_openai_params(self, model: str) -> list[str]:
-        """Return list of supported OpenAI parameters"""
+        """Return list of supported OpenAI parameters.
+
+        A2A has no sampling controls. SendMessageConfiguration carries
+        acceptedOutputModes, taskPushNotificationConfig, historyLength and
+        returnImmediately, nothing else, because the remote agent owns its own
+        model config. Only stream is real here: it picks message/stream over
+        message/send.
+        """
         return [
             "stream",
-            "temperature",
-            "max_tokens",
-            "top_p",
         ]
 
     def map_openai_params(
diff --git a/tests/llm_translation/test_a2a.py b/tests/llm_translation/test_a2a.py
index ec260acd1ae..df77db5b292 100644
--- a/tests/llm_translation/test_a2a.py
+++ b/tests/llm_translation/test_a2a.py
@@ -130,3 +130,38 @@ def test_a2a_completion_sync_streaming():
         pytest.skip(f"A2A agent not reachable at {api_base}: {e}")
     except Exception as e:
         pytest.fail(f"Error occurred: {e}")
+
+
+def test_a2a_only_claims_stream():
+    """A2A has no sampling params, so it must not advertise any.
+
+    Claiming one suppresses the UnsupportedParamsError and the value is
+    dropped without telling the caller.
+    """
+    from litellm.llms.a2a.chat.transformation import A2AConfig
+
+    supported = A2AConfig().get_supported_openai_params("test-agent")
+    assert "stream" in supported
+    for param in ("temperature", "max_tokens", "top_p"):
+        assert param not in supported
+
+
+@pytest.mark.parametrize("param,value", [("temperature", 0.5), ("max_tokens", 100), ("top_p", 0.9)])
+def test_a2a_sampling_params_raise(param, value):
+    """Sampling params should surface an error rather than vanish."""
+    from litellm.utils import get_optional_params
+
+    with pytest.raises(litellm.UnsupportedParamsError):
+        get_optional_params(
+            model="test-agent", custom_llm_provider="a2a", **{param: value}
+        )
+
+
+def test_a2a_stream_still_maps():
+    """stream is the one real param, it must survive."""
+    from litellm.utils import get_optional_params
+
+    params = get_optional_params(
+        model="test-agent", custom_llm_provider="a2a", stream=True
+    )
+    assert params["stream"] is True