Python: fix(claude): preserve $defs in JSON schema for nested Pydantic models (#3655)

* fix(claude): preserve $defs in JSON schema for nested Pydantic models

- Preserve $defs section from Pydantic JSON schema when converting FunctionTool to SDK MCP tool
- This fixes tools with nested Pydantic models that use $ref references
- Add test for nested type schema preservation

Fixes #3654

* Adjust shared state import

* Fix MCP tool kwargs serialization bug

---------

Co-authored-by: Evan Mattson <evan.mattson@microsoft.com>

python/packages/core/agent_framework/_tools.py

@@ -796,11 +796,26 @@ class FunctionTool(BaseTool, Generic[ArgsT, ReturnT]):
 
         attributes = get_function_span_attributes(self, tool_call_id=tool_call_id)
         if OBSERVABILITY_SETTINGS.SENSITIVE_DATA_ENABLED:  # type: ignore[name-defined]
+            # Filter out framework kwargs that are not JSON serializable
+            serializable_kwargs = {
+                k: v
+                for k, v in kwargs.items()
+                if k
+                not in {
+                    "chat_options",
+                    "tools",
+                    "tool_choice",
+                    "thread",
+                    "conversation_id",
+                    "options",
+                    "response_format",
+                }
+            }
             attributes.update({
                 OtelAttr.TOOL_ARGUMENTS: arguments.model_dump_json()
                 if arguments
-                else json.dumps(kwargs)
-                if kwargs
+                else json.dumps(serializable_kwargs, default=str)
+                if serializable_kwargs
                 else "None"
             })
         with get_function_span(attributes=attributes) as span:

python/packages/core/tests/workflow/test_edge.py

@@ -10,7 +10,6 @@ from agent_framework import (
     Executor,
     InProcRunnerContext,
     Message,
-    SharedState,
     WorkflowContext,
     handler,
 )
@@ -24,6 +23,7 @@ from agent_framework._workflows._edge import (
     SwitchCaseEdgeGroupDefault,
 )
 from agent_framework._workflows._edge_runner import create_edge_runner
+from agent_framework._workflows._shared_state import SharedState
 from agent_framework.observability import EdgeGroupDeliveryStatus
 
 # Add for test

python/packages/core/tests/workflow/test_workflow_states.py

@@ -8,7 +8,6 @@ from agent_framework import (
     ExecutorFailedEvent,
     InProcRunnerContext,
     RequestInfoEvent,
-    SharedState,
     Workflow,
     WorkflowBuilder,
     WorkflowContext,
@@ -20,6 +19,7 @@ from agent_framework import (
     WorkflowStatusEvent,
     handler,
 )
+from agent_framework._workflows._shared_state import SharedState
 
 
 class FailingExecutor(Executor):