feat: add meta field support to MCP tool results

src/strands/tools/mcp/mcp_client.py

@@ -564,6 +564,10 @@ def _handle_tool_result(self, tool_use_id: str, call_tool_result: MCPCallToolRes
         if call_tool_result.structuredContent:
             result["structuredContent"] = call_tool_result.structuredContent
 
+        call_tool_result_dict = call_tool_result.model_dump()
+        if call_tool_result_dict.get("meta"):
+            result["meta"] = call_tool_result_dict["meta"]
+
         return result
 
     async def _async_background_thread(self) -> None:

src/strands/tools/mcp/mcp_types.py

@@ -58,6 +58,10 @@ class MCPToolResult(ToolResult):
         structuredContent: Optional JSON object containing structured data returned
             by the MCP tool. This allows MCP tools to return complex data structures
             that can be processed programmatically by agents or other tools.
+        meta: Optional arbitrary metadata returned by the MCP tool. This field allows
+            MCP servers to attach custom metadata to tool results (e.g., token usage,
+            performance metrics, or business-specific tracking information).
     """
 
     structuredContent: NotRequired[Dict[str, Any]]
+    meta: NotRequired[Dict[str, Any]]

tests/strands/tools/mcp/test_mcp_client.py

@@ -723,3 +723,65 @@ async def test_handle_error_message_non_exception():
 
     # This should not raise an exception
     await client._handle_error_message("normal message")
+
+
+def test_call_tool_sync_with_meta_field(mock_transport, mock_session):
+    """Test that call_tool_sync correctly handles meta field."""
+    mock_content = MCPTextContent(type="text", text="Test message")
+    meta_data = {"tokenUsage": {"inputTokens": 100, "outputTokens": 50}, "executionTime": 1.5}
+    mock_session.call_tool.return_value = MCPCallToolResult(isError=False, content=[mock_content], meta=meta_data)
+
+    with MCPClient(mock_transport["transport_callable"]) as client:
+        result = client.call_tool_sync(tool_use_id="test-123", name="test_tool", arguments={"param": "value"})
+
+        mock_session.call_tool.assert_called_once_with("test_tool", {"param": "value"}, None)
+
+        assert result["status"] == "success"
+        assert result["toolUseId"] == "test-123"
+        assert len(result["content"]) == 1
+        assert result["content"][0]["text"] == "Test message"
+        assert "meta" in result
+        assert result["meta"] == meta_data
+        assert result["meta"]["tokenUsage"]["inputTokens"] == 100
+        assert result["meta"]["tokenUsage"]["outputTokens"] == 50
+        assert result["meta"]["executionTime"] == 1.5
+
+
+def test_call_tool_sync_without_meta_field(mock_transport, mock_session):
+    """Test that call_tool_sync works correctly when no meta field is provided."""
+    mock_content = MCPTextContent(type="text", text="Test message")
+    mock_session.call_tool.return_value = MCPCallToolResult(
+        isError=False,
+        content=[mock_content],
+    )
+
+    with MCPClient(mock_transport["transport_callable"]) as client:
+        result = client.call_tool_sync(tool_use_id="test-123", name="test_tool", arguments={"param": "value"})
+
+        assert result["status"] == "success"
+        assert result["toolUseId"] == "test-123"
+        assert len(result["content"]) == 1
+        assert result["content"][0]["text"] == "Test message"
+        assert result.get("meta") is None
+
+
+def test_call_tool_sync_with_meta_and_structured_content(mock_transport, mock_session):
+    """Test that call_tool_sync correctly handles both meta and structuredContent fields."""
+    mock_content = MCPTextContent(type="text", text="Test message")
+    meta_data = {"tokenUsage": {"inputTokens": 100, "outputTokens": 50}}
+    structured_content = {"result": 42, "status": "completed"}
+    mock_session.call_tool.return_value = MCPCallToolResult(
+        isError=False, content=[mock_content], meta=meta_data, structuredContent=structured_content
+    )
+
+    with MCPClient(mock_transport["transport_callable"]) as client:
+        result = client.call_tool_sync(tool_use_id="test-123", name="test_tool", arguments={"param": "value"})
+
+        mock_session.call_tool.assert_called_once_with("test_tool", {"param": "value"}, None)
+
+        assert result["status"] == "success"
+        assert result["toolUseId"] == "test-123"
+        assert "meta" in result
+        assert result["meta"] == meta_data
+        assert "structuredContent" in result
+        assert result["structuredContent"] == structured_content