DC-2872: Block generic OTel MCP contrib when MCP opt-in is off

.github/workflows/pr_build.yaml

@@ -75,7 +75,7 @@ jobs:
       - name: Unit tests
         run: |
           export RUN_SDK_INTEGRATION_TESTS=1
-          python -m pytest --log-cli-level=INFO --tb=long
+          python -m pytest -p scripts.litellm_pydantic_pytest_plugin --log-cli-level=INFO --tb=long
         env:
           PYTHONUNBUFFERED: 1
           HA_ENABLE_CONSOLE_SPAN_EXPORTER: "true"
@@ -84,7 +84,7 @@ jobs:
         if: matrix.python-version == '3.12'
         run: |
           export RUN_SDK_INTEGRATION_TESTS=1
-          python -m pytest --log-cli-level=INFO --tb=long \
+          python -m pytest -p scripts.litellm_pydantic_pytest_plugin --log-cli-level=INFO --tb=long \
             --cov=harness_sdk --cov-report=xml:coverage.xml --junitxml=pytest-report.xml
         env:
           PYTHONUNBUFFERED: 1

scripts/litellm_pydantic_pytest_plugin.py

@@ -0,0 +1,25 @@
+"""Pytest plugin to rebuild litellm pydantic models in the test process."""
+
+
+def pytest_configure(config):  # pylint: disable=unused-argument
+    try:
+        from litellm.types.llms.openai import (  # noqa: F401
+            ChatCompletionReasoningSummaryTextBlock,
+        )
+        import litellm.types.utils as litellm_utils
+        from pydantic import BaseModel
+    except ImportError:
+        return
+
+    for name in dir(litellm_utils):
+        obj = getattr(litellm_utils, name)
+        if (
+            isinstance(obj, type)
+            and issubclass(obj, BaseModel)
+            and obj is not BaseModel
+            and hasattr(obj, "model_rebuild")
+        ):
+            try:
+                obj.model_rebuild()
+            except Exception:
+                pass

src/harness_sdk/instrumentation/instrumentation_definitions.py

@@ -164,6 +164,7 @@ def _mark_as_instrumented(library_key, wrapper_instance):
     "groq",
     "langchain",
     "llamaindex",
+    "mcp",
     "mistralai",
     "ollama",
     "replicate",

test/instrumentation/test_instrumentation_definitions.py

@@ -160,6 +160,17 @@ def test_instrument_skips_denylisted_libraries():
     assert "aiobotocore" not in _GENERIC_INSTRUMENTATION_STATE
 
 
+def test_instrument_skips_mcp_generic_contrib():
+    mcp_ep = _make_entry_point("mcp")
+
+    with patch("harness_sdk.instrumentation.instrumentation_definitions._get_contrib_instrumentation_entry_points",
+               return_value=[mcp_ep]):
+        instrument_supported_contrib_without_wrapper()
+
+    mcp_ep.load.assert_not_called()
+    assert "mcp" not in _GENERIC_INSTRUMENTATION_STATE
+
+
 def test_instrument_skips_ai_focused_generic_instrumentors():
     langchain_ep = _make_entry_point("langchain")