As reported in the bbc article available here: https://www.bbc.co.uk/news/uk-politics-47742395
The UK government has split the 'deal' into the actual agreement and the non-legally binding political declaration - an explanation of which is available here: https://www.bbc.co.uk/news/uk-politics-46303751
Since it seems more like a statement of intent than anything else, why would the government need parliament to vote on it at all? Couldn't they just get the actual agreement through, then say "You've had your meaningful vote. Deal with it."