From 41e7fb53dcf84c0f731f8eb265e549cc31fa7f73 Mon Sep 17 00:00:00 2001
From: Saquib Jawed <138011435+saquibjawedbit@users.noreply.github.com>
Date: Tue, 22 Sep 2026 19:21:14 +0530
Subject: [PATCH 1/2] Python: Keep Field constraints after an Annotated tool
 description

_parse_annotation wrapped the metadata that follows a string description
in a single tuple, so Pydantic ignored it. Constraints such as
Field(ge=1, le=10) were missing from the tool schema and not enforced
when the tool was invoked. Unpack the remaining metadata instead.

Fixes #8643
---
 .../packages/core/agent_framework/_tools.py   |  2 +-
 python/packages/core/tests/core/test_tools.py | 37 +++++++++++++++++++
 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/python/packages/core/agent_framework/_tools.py b/python/packages/core/agent_framework/_tools.py
index bfde7930c10..f75588e20b7 100644
--- a/python/packages/core/agent_framework/_tools.py
+++ b/python/packages/core/agent_framework/_tools.py
@@ -1471,7 +1471,7 @@ def _parse_annotation(annotation: Any) -> Any:
             args_list = list(args)
             if len(args_list) == 2:
                 return Annotated[args_list[0], Field(description=args_list[1])]
-            return Annotated[args_list[0], Field(description=args_list[1]), tuple(args_list[2:])]
+            return Annotated[(args_list[0], Field(description=args_list[1]), *args_list[2:])]
     return annotation
 
 
diff --git a/python/packages/core/tests/core/test_tools.py b/python/packages/core/tests/core/test_tools.py
index 3071e191513..9269af4fc46 100644
--- a/python/packages/core/tests/core/test_tools.py
+++ b/python/packages/core/tests/core/test_tools.py
@@ -1565,6 +1565,43 @@ def test_parse_annotation_with_annotated_and_literal():
     assert get_args(literal_type) == ("A", "B", "C")
 
 
+def test_parse_annotation_with_description_preserves_extra_metadata():
+    """Test that metadata after a string description is kept as separate Annotated metadata."""
+    from pydantic import Field
+
+    constraints = Field(ge=1, le=10)
+    result = _parse_annotation(Annotated[int, "How many items", constraints])
+
+    assert get_origin(result) is Annotated
+    args = get_args(result)
+    assert args[0] is int
+    assert args[1].description == "How many items"
+    assert args[2] is constraints
+
+
+async def test_tool_annotated_description_keeps_field_constraints():
+    """Test that Field constraints after a string description reach the schema and validation."""
+    from pydantic import Field
+
+    @tool
+    def pick(count: Annotated[int, "How many items", Field(ge=1, le=10)]) -> str:
+        return str(count)
+
+    assert pick.parameters()["properties"]["count"] == {
+        "description": "How many items",
+        "maximum": 10,
+        "minimum": 1,
+        "title": "Count",
+        "type": "integer",
+    }
+
+    result = await pick.invoke(arguments={"count": 5})
+    assert result[0].text == "5"
+
+    with pytest.raises(TypeError, match="less than or equal to 10"):
+        await pick.invoke(arguments={"count": 999})
+
+
 # endregion
 
 

From 6b2a4b39dbd818a7a8f5bb81f43cbe9e6ac5481a Mon Sep 17 00:00:00 2001
From: Saquib Jawed <138011435+saquibjawedbit@users.noreply.github.com>
Date: Tue, 22 Sep 2026 22:30:02 +0530
Subject: [PATCH 2/2] Python: Assert only the relevant schema keys and Pydantic
 error type in the Annotated constraint test

---
 python/packages/core/tests/core/test_tools.py | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/python/packages/core/tests/core/test_tools.py b/python/packages/core/tests/core/test_tools.py
index 9269af4fc46..c20c72a3148 100644
--- a/python/packages/core/tests/core/test_tools.py
+++ b/python/packages/core/tests/core/test_tools.py
@@ -1587,18 +1587,15 @@ async def test_tool_annotated_description_keeps_field_constraints():
     def pick(count: Annotated[int, "How many items", Field(ge=1, le=10)]) -> str:
         return str(count)
 
-    assert pick.parameters()["properties"]["count"] == {
-        "description": "How many items",
-        "maximum": 10,
-        "minimum": 1,
-        "title": "Count",
-        "type": "integer",
-    }
+    count_schema = pick.parameters()["properties"]["count"]
+    assert count_schema["description"] == "How many items"
+    assert count_schema["minimum"] == 1
+    assert count_schema["maximum"] == 10
 
     result = await pick.invoke(arguments={"count": 5})
     assert result[0].text == "5"
 
-    with pytest.raises(TypeError, match="less than or equal to 10"):
+    with pytest.raises(TypeError, match="less_than_equal"):
         await pick.invoke(arguments={"count": 999})