Essex 343 and 59 for 2 (Das 27*, Hume 2-14) trail Ireland 419 (Stirling 107, Tucker 97, McBrine 67, Richards 5-96) by 17 runs
Stirling, who scored his first Test hundred in Galle last month, had been expected to miss the game against England because of a deal to play in the Blast for Birmingham Bears, but was picked in the squad after a change of heart.
He only joined the tour match in Chelmsford on Saturday, having turned out for Birmingham in Leicester less than 24 hours previously, and was quickly making the adjustment to facing a red ball after walking out in the sixth over of the morning.
However, Stirling and Tucker set about repairing the damage with a stand that was eventually worth 175 in 30.1 overs.
Stirling brought up his half-century first, from 63 balls, with Tucker getting to the mark from 61 balls shortly after. Tucker, the wicketkeeper-batter, then accelerated towards a century with a flurry of boundaries, but required treatment for an arm problem on 96 and then cut tamely to backward point a few balls later.