fix: support list of types

Author: NicoleMGomes

src/sap_cloud_sdk/agentgateway/converters.py

@@ -26,6 +26,19 @@
 }
 
 
+def _resolve_type(json_type: Any) -> tuple[type, bool]:
+    """Return (python_type, is_nullable) from a JSON Schema ``type`` value.
+
+    Handles both the plain-string form (``"integer"``) and the array form
+    (``["integer", "null"]``).  Unknown or missing types map to ``Any``.
+    """
+    if isinstance(json_type, list):
+        nullable = "null" in json_type
+        scalar = next((t for t in json_type if t != "null"), None)
+        return _JSON_TYPE_MAP.get(scalar, Any), nullable
+    return _JSON_TYPE_MAP.get(json_type, Any), False
+
+
 def mcp_tool_to_langchain(
     mcp_tool: MCPTool,
     call_tool: Callable,
@@ -91,17 +104,14 @@ async def run(**kwargs) -> str:
     # Build args schema from input_schema
     properties = mcp_tool.input_schema.get("properties", {})
     required = set(mcp_tool.input_schema.get("required", []))
-    fields: dict[str, Any] = {
-        k: (
-            (_JSON_TYPE_MAP.get(v.get("type", ""), Any), ...)
-            if k in required
-            else (
-                _JSON_TYPE_MAP.get(v.get("type", ""), Any) | None,
-                Field(default=None),
-            )
-        )
-        for k, v in properties.items()
-    }
+    fields: dict[str, Any] = {}
+    for k, v in properties.items():
+        py_type, type_nullable = _resolve_type(v.get("type"))
+        optional = k not in required
+        if optional or type_nullable:
+            fields[k] = (py_type | None, Field(default=None))
+        else:
+            fields[k] = (py_type, ...)
     args_schema = create_model(f"{mcp_tool.name}_args", **fields) if fields else None
 
     return StructuredTool.from_function(

tests/agentgateway/unit/test_converters.py

@@ -185,6 +185,52 @@ def test_optional_non_string_field_is_nullable(self):
         assert int in field.annotation.__args__
         assert type(None) in field.annotation.__args__
 
+    def test_array_type_integer_null_maps_to_int(self):
+        lc_tool = mcp_tool_to_langchain(
+            self._tool_with_types({"limit": {"type": ["integer", "null"]}}, required=["limit"]),
+            AsyncMock(),
+            lambda: "token",
+        )
+        field = _schema_fields(lc_tool)["limit"]
+        import types as _types
+        assert isinstance(field.annotation, _types.UnionType)
+        assert int in field.annotation.__args__
+        assert type(None) in field.annotation.__args__
+
+    def test_array_type_number_null_maps_to_float(self):
+        lc_tool = mcp_tool_to_langchain(
+            self._tool_with_types({"ratio": {"type": ["number", "null"]}}, required=["ratio"]),
+            AsyncMock(),
+            lambda: "token",
+        )
+        field = _schema_fields(lc_tool)["ratio"]
+        import types as _types
+        assert isinstance(field.annotation, _types.UnionType)
+        assert float in field.annotation.__args__
+        assert type(None) in field.annotation.__args__
+
+    def test_array_type_multiple_scalars_uses_first_non_null(self):
+        # e.g. {"type": ["number", "string", "null"]} — pick "number"
+        lc_tool = mcp_tool_to_langchain(
+            self._tool_with_types({"val": {"type": ["number", "string", "null"]}}, required=["val"]),
+            AsyncMock(),
+            lambda: "token",
+        )
+        field = _schema_fields(lc_tool)["val"]
+        import types as _types
+        assert isinstance(field.annotation, _types.UnionType)
+        assert float in field.annotation.__args__
+        assert type(None) in field.annotation.__args__
+
+    def test_array_type_without_null_is_not_nullable(self):
+        lc_tool = mcp_tool_to_langchain(
+            self._tool_with_types({"count": {"type": ["integer"]}}, required=["count"]),
+            AsyncMock(),
+            lambda: "token",
+        )
+        field = _schema_fields(lc_tool)["count"]
+        assert field.annotation is int
+
 
 class TestMcpToolToLangchainInvocation:
     """End-to-end invocation tests: verify what actually reaches call_tool."""