I don't have To Arms, I read it but don't recall what he said specifically about the Russian War plans and Strachan's general book on the war has few details.
Now I had some more success with a book by Keegen.
The French had been pressuring the Russians to agree fully agree to attack by D+15 for some time and then in 1913 had success.
"...extract from General Zhilinshky, the Russian Chief of Staff, a promise that his army would attack Germany with at least 800,000 men - half its peacetime strength 'after M +15,' fifteen days from mobilization. The promise was made specif - 'on' rather than 'after' M +15 - in Article III of the Russia-French Military Convention of September 1913."
John Keegan, The First World War (Knope, New York, 1999) pg 40-41.
On page 40 Keegan makes fairly clear that the French had attached great importance to getting Russia to agree to a joint attack. Before the 1913 agreement Russia had promised vague action to attack some time after D+15.
I did find this online. Its purported to be a translation of the 1913 convention. With attached commentary on the French side.
http://www.vlib.us/wwi/resources/archives/texts/t041012.html
Please note the French Commentary to the preamble.
"The two chiefs of the general staffs declared by common agreement that the words "defensive war" do not mean a war conducted defensively. They assert the contrary, that it is absolutely necessary for the French and Russian armies to take vigorous offensives and as far as possible simultaneously, according to the text of Article 3 of the Convention."
Emphasis added by me.
It should be noted that the French Commentary to Article 3 they were clearly expecting the Germans to come after them.
So I think its fairly clear that France was setting a great deal on Russia to attack Germany. Also clearly France had expected for them to be the main focus. Now despite this France adopted an offensive stance. Why is France going to expect Russia to not do the same just because the Germans are going east?
Again it might be logical and make more sense for Russia to sit on the defensive but if they do Paris is going to livid. That is my view.
Michael