From 3b6c0b05ca0da832f1b027491ee3b70f09ca98a9 Mon Sep 17 00:00:00 2001
From: Giles Odigwe <gilesodigwe@microsoft.com>
Date: Fri, 21 Nov 2025 09:24:30 -0800
Subject: [PATCH 1/2] mcp tool parameter fix

---
 python/packages/core/agent_framework/_mcp.py | 28 ++++++++++++------
 python/packages/core/tests/core/test_mcp.py  | 30 ++++++++++++++++++++
 2 files changed, 50 insertions(+), 8 deletions(-)

diff --git a/python/packages/core/agent_framework/_mcp.py b/python/packages/core/agent_framework/_mcp.py
index 586ebd8df1..1777c76707 100644
--- a/python/packages/core/agent_framework/_mcp.py
+++ b/python/packages/core/agent_framework/_mcp.py
@@ -278,18 +278,30 @@ def resolve_type(prop_details: dict[str, Any]) -> type:
         python_type = resolve_type(prop_details)
         description = prop_details.get("description", "")
 
+        # Handle array types
+        field_kwargs: dict[str, Any] = {}
+        if description:
+            field_kwargs["description"] = description
+
+        # Preserve array items schema if present
+        if prop_details.get("type") == "array" and "items" in prop_details:
+            items_schema = prop_details["items"]
+            if items_schema and items_schema != {}:
+                field_kwargs["json_schema_extra"] = {"items": items_schema}
+
         # Create field definition for create_model
         if prop_name in required:
-            field_definitions[prop_name] = (
-                (python_type, Field(description=description)) if description else (python_type, ...)
-            )
+            if field_kwargs:
+                field_definitions[prop_name] = (python_type, Field(**field_kwargs))
+            else:
+                field_definitions[prop_name] = (python_type, ...)
         else:
             default_value = prop_details.get("default", None)
-            field_definitions[prop_name] = (
-                (python_type, Field(default=default_value, description=description))
-                if description
-                else (python_type, default_value)
-            )
+            field_kwargs["default"] = default_value
+            if field_kwargs and any(k != "default" for k in field_kwargs):
+                field_definitions[prop_name] = (python_type, Field(**field_kwargs))
+            else:
+                field_definitions[prop_name] = (python_type, default_value)
 
     return create_model(f"{tool.name}_input", **field_definitions)
 
diff --git a/python/packages/core/tests/core/test_mcp.py b/python/packages/core/tests/core/test_mcp.py
index 34f4857dc2..ea33ae9107 100644
--- a/python/packages/core/tests/core/test_mcp.py
+++ b/python/packages/core/tests/core/test_mcp.py
@@ -483,6 +483,36 @@ def test_get_input_model_from_mcp_tool_with_ref_schema():
     assert dumped == {"params": {"customer_id": 251}}
 
 
+def test_get_input_model_from_mcp_tool_with_simple_array():
+    """Test array without complex items schema (should not add json_schema_extra)."""
+    tool = types.Tool(
+        name="simple_array_tool",
+        description="Tool with simple array",
+        inputSchema={
+            "type": "object",
+            "properties": {
+                "tags": {
+                    "type": "array",
+                    "description": "List of tags",
+                    "items": {"type": "string"},  # Simple string array
+                }
+            },
+            "required": ["tags"],
+        },
+    )
+    model = _get_input_model_from_mcp_tool(tool)
+
+    # Create an instance
+    instance = model(tags=["tag1", "tag2", "tag3"])
+    assert instance.tags == ["tag1", "tag2", "tag3"]
+
+    # Verify JSON schema still preserves items for simple types
+    json_schema = model.model_json_schema()
+    tags_property = json_schema["properties"]["tags"]
+    assert "items" in tags_property
+    assert tags_property["items"]["type"] == "string"
+
+
 def test_get_input_model_from_mcp_prompt():
     """Test creation of input model from MCP prompt."""
     prompt = types.Prompt(

From 115e1d4b3c2cae0b7a468841a1b17ba990b7859b Mon Sep 17 00:00:00 2001
From: Giles Odigwe <gilesodigwe@microsoft.com>
Date: Fri, 21 Nov 2025 09:40:26 -0800
Subject: [PATCH 2/2] small fixes

---
 python/packages/core/agent_framework/_mcp.py | 2 +-
 python/packages/core/tests/core/test_mcp.py  | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/python/packages/core/agent_framework/_mcp.py b/python/packages/core/agent_framework/_mcp.py
index 1777c76707..6e4c71fe49 100644
--- a/python/packages/core/agent_framework/_mcp.py
+++ b/python/packages/core/agent_framework/_mcp.py
@@ -278,7 +278,7 @@ def resolve_type(prop_details: dict[str, Any]) -> type:
         python_type = resolve_type(prop_details)
         description = prop_details.get("description", "")
 
-        # Handle array types
+        # Build field kwargs (description, array items schema, etc.)
         field_kwargs: dict[str, Any] = {}
         if description:
             field_kwargs["description"] = description
diff --git a/python/packages/core/tests/core/test_mcp.py b/python/packages/core/tests/core/test_mcp.py
index ea33ae9107..b73136fd6b 100644
--- a/python/packages/core/tests/core/test_mcp.py
+++ b/python/packages/core/tests/core/test_mcp.py
@@ -484,7 +484,7 @@ def test_get_input_model_from_mcp_tool_with_ref_schema():
 
 
 def test_get_input_model_from_mcp_tool_with_simple_array():
-    """Test array without complex items schema (should not add json_schema_extra)."""
+    """Test array with simple items schema (items schema should be preserved in json_schema_extra)."""
     tool = types.Tool(
         name="simple_array_tool",
         description="Tool with simple array",