fix(shared): make UrlElicitationRequiredError pickle-safe

Signed-off-by: ulofiai <monsterking@tutamail.com>

Author: ulofiai

src/mcp/shared/exceptions.py

@@ -107,6 +107,10 @@ def elicitations(self) -> list[ElicitRequestURLParams]:
         """The list of URL elicitations required before the request can proceed."""
         return self._elicitations
 
+    def __reduce__(self) -> tuple[type, tuple[list[ElicitRequestURLParams], str]]:
+        """Support pickling by reconstructing with the original constructor signature."""
+        return (self.__class__, (self._elicitations, self.message))
+
     @classmethod
     def from_error(cls, error: ErrorData) -> UrlElicitationRequiredError:
         """Reconstruct from an ErrorData received over the wire."""

tests/shared/test_exceptions.py

@@ -1,5 +1,7 @@
 """Tests for MCP exception classes."""
 
+import pickle
+
 import pytest
 from mcp_types import URL_ELICITATION_REQUIRED, ElicitRequestURLParams, ErrorData, JSONRPCError
 
@@ -173,3 +175,38 @@ def test_from_jsonrpc_error_preserves_code_message_and_data() -> None:
     )
     error = MCPError.from_jsonrpc_error(wire)
     assert error.error == ErrorData(code=URL_ELICITATION_REQUIRED, message="go elsewhere", data={"hint": "y"})
+
+
+def test_mcp_error_pickle_roundtrip() -> None:
+    """MCPError preserves its structured payload across a pickle round-trip."""
+    original = MCPError(code=-32600, message="Invalid request", data={"detail": "bad"})
+
+    restored = pickle.loads(pickle.dumps(original))
+
+    assert type(restored) is MCPError
+    assert restored.error == original.error
+
+
+def test_url_elicitation_required_error_pickle_roundtrip() -> None:
+    """UrlElicitationRequiredError preserves its typed state when pickled."""
+    elicitations = [
+        ElicitRequestURLParams(
+            mode="url",
+            message="First authorization",
+            url="https://example.com/auth/first",
+            elicitation_id="auth-1",
+        ),
+        ElicitRequestURLParams(
+            mode="url",
+            message="Second authorization",
+            url="https://example.com/auth/second",
+            elicitation_id="auth-2",
+        ),
+    ]
+    original = UrlElicitationRequiredError(elicitations, message="Authorization required")
+
+    restored = pickle.loads(pickle.dumps(original))
+
+    assert type(restored) is UrlElicitationRequiredError
+    assert restored.error == original.error
+    assert restored.elicitations == original.elicitations