Python: fix(tools): preserve UTF-8 characters without unicode escaping in tool results

python/packages/core/agent_framework/_mcp.py

@@ -1304,7 +1304,7 @@ def _parse_prompt_result_from_mcp(
             return ""
         if len(parts) == 1:
             return parts[0]
-        return json.dumps(parts, default=str)
+        return json.dumps(parts, default=str, ensure_ascii=False)
 
     def _parse_message_from_mcp(
         self,
@@ -1390,7 +1390,7 @@ def _parse_tool_result_from_mcp(
         structured_block: Content | None = None
         if mcp_type.structured_content is not None:
             structured_block = Content.from_text(
-                json.dumps(mcp_type.structured_content, default=str), **additional_kwargs
+                json.dumps(mcp_type.structured_content, default=str, ensure_ascii=False), **additional_kwargs
             )
 
         # Select model-visible content per explicit policy (#7866). Host payload still

python/packages/core/agent_framework/_tools.py

@@ -1413,13 +1413,15 @@ def parse_result(result: Any) -> list[Content]:
                     parsed_items.append(item)
                 else:
                     dumpable = FunctionTool._make_dumpable(item)
-                    text = dumpable if isinstance(dumpable, str) else json.dumps(dumpable, default=str)
+                    text = (
+                        dumpable if isinstance(dumpable, str) else json.dumps(dumpable, default=str, ensure_ascii=False)
+                    )
                     parsed_items.append(Content.from_text(text))
             return parsed_items
         dumpable = FunctionTool._make_dumpable(result)
         if isinstance(dumpable, str):
             return [Content.from_text(dumpable)]
-        return [Content.from_text(json.dumps(dumpable, default=str))]
+        return [Content.from_text(json.dumps(dumpable, default=str, ensure_ascii=False))]
 
     def to_json_schema_spec(self) -> dict[str, Any]:
         """Convert a FunctionTool to the JSON Schema function specification format.

python/packages/core/agent_framework/_types.py

@@ -1202,7 +1202,7 @@ def from_function_result(
             items_list = [Content.from_text(result)]
         elif result is not None:
             try:
-                text = json.dumps(result, default=str)
+                text = json.dumps(result, default=str, ensure_ascii=False)
             except (TypeError, ValueError):
                 text = str(result)
             items_list = [Content.from_text(text)]

python/packages/core/tests/core/test_mcp.py

@@ -1104,6 +1104,31 @@ def test_mcp_tool_str_and_parse_prompt_result_rich_content() -> None:
     }
 
 
+def test_parse_prompt_result_from_mcp_unicode_unescaped():
+    """Test that non-ASCII unicode characters in multi-message prompt results are not escaped to \\uXXXX."""
+    tool = _HELPER_MCP_TOOL
+    prompt_result = types.GetPromptResult(
+        description="Unicode prompt",
+        messages=[
+            types.PromptMessage(
+                role="user",
+                content=types.TextContent(type="text", text="Año"),
+            ),
+            types.PromptMessage(
+                role="assistant",
+                content=types.TextContent(type="text", text="Género"),
+            ),
+        ],
+    )
+
+    result = tool._parse_prompt_result_from_mcp(prompt_result)
+
+    assert "Año" in result
+    assert "Género" in result
+    assert "\\u00f1" not in result
+    assert "\\u00e9" not in result
+
+
 def test_parse_tool_result_from_mcp():
     """Test conversion from MCP tool result with images preserves original order."""
     mcp_result = types.CallToolResult(
@@ -1254,6 +1279,25 @@ def test_parse_tool_result_from_mcp_structured_content_only():
     assert parsed == {"Tables": [{"Name": "Sales", "Columns": ["Amount", "Date"]}]}
 
 
+def test_parse_tool_result_from_mcp_structured_content_unicode_unescaped():
+    """Test that non-ASCII unicode characters in structured_content are not escaped to \\uXXXX."""
+    mcp_result = types.CallToolResult(
+        content=[],
+        structured_content={"columns": ["Año", "Género", "Categoría"]},
+    )
+    result = _HELPER_MCP_TOOL._parse_tool_result_from_mcp(mcp_result)
+
+    assert isinstance(result, list)
+    assert len(result) == 1
+    assert result[0].text is not None
+    assert "Año" in result[0].text
+    assert "Género" in result[0].text
+    assert "Categoría" in result[0].text
+    assert "\\u00f1" not in result[0].text
+    assert "\\u00e9" not in result[0].text
+    assert "\\u00ed" not in result[0].text
+
+
 def test_parse_tool_result_from_mcp_structured_content_with_text():
     """Default structured_first prefers structuredContent when both are present (#7866)."""
     mcp_result = types.CallToolResult(

python/packages/core/tests/core/test_types.py

@@ -4653,6 +4653,40 @@ def test_parse_result_mixed_content_list():
     assert result[1].type == "data"
 
 
+def test_parse_result_non_ascii_unicode():
+    """Test that non-ASCII unicode characters in dict results are not escaped to \\uXXXX."""
+    data = {"columns": ["Año", "Género", "Categoría"]}
+    parsed = FunctionTool.parse_result(data)
+    assert len(parsed) == 1
+    assert parsed[0].text is not None
+    assert "Año" in parsed[0].text
+    assert "Género" in parsed[0].text
+    assert "\\u00f1" not in parsed[0].text
+    assert "\\u00e9" not in parsed[0].text
+
+
+def test_parse_result_list_non_ascii_unicode():
+    """Test that non-ASCII unicode in list-of-items results are not escaped to \\uXXXX."""
+    data = [{"name": "Año"}, {"name": "Género"}]
+    parsed = FunctionTool.parse_result(data)
+    assert len(parsed) == 1
+    assert parsed[0].text is not None
+    assert "Año" in parsed[0].text
+    assert "Género" in parsed[0].text
+    assert "\\u00f1" not in parsed[0].text
+
+
+def test_from_function_result_non_ascii_unicode():
+    """Test that Content.from_function_result preserves UTF-8 unicode in dict results."""
+    data = {"city": "München", "country": "España"}
+    content = Content.from_function_result(call_id="call-1", result=data)
+    assert content.result is not None
+    assert "München" in content.result
+    assert "España" in content.result
+    assert "\\u00fc" not in content.result
+    assert "\\u00f1" not in content.result
+
+
 def test_from_function_result_with_content_list():
     """Test Content.from_function_result stores all items uniformly."""
     content_list = [