Could that problems between Halleck and McClellan be more of a failure in communication and mistrust. McClellan unable or unwilling tell Halleck his ideas and Halleck seeing a general who has no plans. Some of McClellan's questions at this time border on the tedious.
So I should note here that the time delay in messages going on before McClellan leaves Harrisons is:
A message from Harrisons to Washington would take ten hours to get to Jamestown Island (by dispatch boat), then would be transmitted to Washington on an eight-plus step communication wire (Jamestown Island to Yorktown to Newport News to Fort Monroe to Cape Charles/Cherrystone Inlet to Lewes to Dover to Wilmington to Washington). These lines were (I believe) boosted enough that they were a single circuit, but it still meant that a ~500 word message took half an hour to transmit.
This means that if McClellan and Halleck are having a conversation from their respective HQs then the turnaround time (assuming that both are awake when the message for them arrives and they can quickly compose their reply) is about a day.
If those lines were places where an operator had to re-key out the message, it would be considerably longer.
Up until the July 26 meeting, McClellan is constantly being told that there are reinforcements en route, and he is trying to find out when they will arrive. (That's Burnside.) On at least one occasion he is given an expected time, but the expected time expires without explanation.
At the July 26 meeting (with Halleck in person), McClellan agrees to advance once Burnside arrives. He will be advancing straight towards Richmond, because the pontoons required to go after Petersburg have not been forthcoming (McClellan asked for them 3-4 weeks ago.)
In a message sent afterwards, McClellan confirms that he will be advancing, and adds that extra troops would be helpful but does not make them a precondition of advancing.
July 27, Lee sends AP Hill to Madison Court House, with orders to be ready to return if needed.
July 30, Halleck tells McClellan to check if the force in Richmond is small. (McClellan gets this August 1st.) Halleck also tells McClellan to send off his sick.
July 31, Halleck sends McClellan a rumour that the enemy is evacuating Richmond. This also reaches McClellan on August 1st.
(Note that at this time most of Lee's force was still at Richmond.)
August 1, Halleck orders Burnside to Aquia (reneging on the reinforcement deal).
August 2, McClellan orders Hooker to retake Malvern Hill overnight. This fails owing to the guides getting lost.
Halleck telegrams again about the sending off of the sick, wanting an answer about when they will be out of the way.
August 3: McClellan occupies Coggins Point, both as a possible debouche and to prevent further bombardment raids.
He also replies to Halleck about how long it will take to get off the sick, giving the numbers - he can embark 1,200 at a time, and has 12,500, though 4,000 are "walking wounded" who can make easy marches. His estimate for the amount of time it would take is "from seven to ten days".
August 4:
McClellan recieves an order from Halleck to withdraw the army to Aquia, to which he strongly protests. Halleck's order complains that McClellan hasn't answered his questions or done a recce towards Richmond (which is because of the telegraph delay - McClellan has answered the question, but Halleck hasn't allowed time for the message to reach McClellan, McClellan to reply and the reply to reach Halleck), and tells McClellan "your material and transportation should be removed first" (i.e. don't abandon a bonanza of supplies for the Confederates, or destroy them en masse).
McClellan protests against the order, first arguing that there are reinforcements available (Burnside's force, just for starters) and in general trying to get across that his position is a good one for attacking Richmond.
Hooker moves overnight for the seond time, and this time he's successful, gaining Malvern Hill overnight. McClellan reports this on the morning of the 5th.
August 5: Cavalry recces reach past White Oak Swamp bridge. McClellan is definitively advancing towards Richmond. (This causes Lee severe worry, and he pulls together everything he has near Richmond to respond.)
August 6: Further orders from Halleck arrive, telling McClellan that "I have no reinforcements to give you" and also asking him to give up some cavalry and artillery to go to Burnside at Aquia Creek (this will be reiterated a day or two later).
Based on this and on the order to move to Aquia, McClellan cancels his movement against Richmond and pulls Hooker back.
The morning of the 9th is when the batteries for Burnside leave. It's also the date at which Lee decides to send Longstreet to Gordonsville, ordering Longstreet's 6-brigade division there.
On the 9th, Halleck complains that McClellan must send reinforcements "instantly" to Aquia, and says that with all the transports available the delay is not satisfactory.
McClellan on the morning of the 10th replies by saying that the sick are still being loaded, and that he's just got enough transport (after sending the batteries off) to load one regiment of cavalry for Burnside.
Recall that back when he was asked McClellan said on the 3rd that it would take seven to ten days to get all the sick sent off; since then he's had the shipping for five batteries and one cavalry regiment diverted from that purpose.
Late on the 10th another telegram arrives, in which Halleck says that the delay in McClellan's movements is "entirely unexpected, and must be satisfactorily explained". McClellan replies before midnight, pointing out the issue of transport that he's raised more than once, and that he's run out of transports before running out of sick.
On the 11th McClellan reports that he's almost finished loading the cavalry and one brigade of infantry (the reinforcements he was asked to send to Aquia) and that he's still loading sick; there are 4,000 to go.
From the 9th to the 11th, Longstreet's wing departs Richmond for Gordonsville.
On the 12th Lee gets a report to the effect that McClellan is advancing via Malvern Hill. This seems to be the result of a recce by Pleasonton,and on this day McClellan manages to correctly detect that a large Confederate force has been sent to Gordonsville, leaving Richmond weak north of the James (as much of what's left around Richmond is south of the James either around Petersburg or around Drewry's Bluff - also correct). McClellan suggests the idea of an offensive movement to Halleck's consideration, but says that under his current orders he can't unilaterially advance.
McClellan goes down to the telegraph office on the 13th (actually all the way to the Eastern Shore, a journey of well over seventy miles, as there's a problem with the undersea cable across the Chesapeake) to try and talk with Halleck directly over the telegraph, but Halleck refuses to do so - he simply says there's no change in plans and leaves the office.
After McClellan reaches Alexandria, what he wants is for Halleck to give direction. Either Halleck wants 2nd and 6th Corps to defend Alexandria, or he wants them to be properly equipped and then march out, or he wants them to head out immediately.
What McClellan is doing in this period is trying to get the authorization to properly equip 2nd and 6th Corps, or alternatively to get the instruction that he shouldn't be bothering to properly equip 2nd and 6th Corps, or possibly an order to march 2nd and 6th Corps out immediately. But McClellan needs to know which it is.
At the time Halleck's instructions were to equip and then move out, and McClellan is trying to do that, but he does not have authority over Banks' wagon trains which are left in Washington and which are the only realistic source of wagon equipment. He needs authorization from Halleck because he is specifically
not the commander of those assets (they are part of Pope's army).
What sort of thing are you thinking of as being "tedious"?
When Sherman reached Savannah, Grant ordered him to put most of his men on ships and send them to him. Sherman wrote back explaining his thoughts why it was a bad idea, not once but numerous times. Sherman and Grant could work together Sherman didn't fall back on the excuse that Grant was GIC.
Are you advocating that McClellan should have disobeyed the legally constituted orders of his superior?