Daniel Sturridge's 50th career league goal - and his 24th in 30 games for the club - put the visitors on course to retain their four-point cushion over Everton in the Barclays Premier League.
However, Toure's misplaced pass straight into the path of former Toffees striker Victor Anichebe midway through the second half put paid to that.
A draw gave more ammunition to the critics who felt Liverpool should have strengthened in the transfer window to enhance their bid to regain Champions League football.
But it was not the absence of Ukrainian winger Yehven Konoplyanka, whose proposed move to Anfield broke down in final hours of the January transfer window, which ultimately cost them points but a lack of resources at the back.
Toure is only playing because Daniel Agger and Mamadou Sakho are injured, but manager Brendan Rodgers insisted defensive reinforcements were not his priority.
Some would argue neither was a winger, but for all the accusations and apportioning of blame fired from east to west and back again over the collapse of the Konoplyanka deal, it should not matter if the strikers keep scoring and the defence keep clean sheets.
Despite Dnipro suggesting Liverpool did not transfer the necessary funds in time, Press Association Sport understands the money was sent at least two hours before the UK's 11pm deadline.
The move, with the player's medical passed and terms agreed, was blocked by the club's owner Ihor Kolomoyskyi who refused to sign off the necessary paperwork, which is believed to have prompted a subsequent apology to Liverpool from Dnipro officials.
Essentially what Liverpool really need is to keep Luis Suarez and Sturridge fit and firing, and while at least one of them kept up that end of the bargain there were failings elsewhere at the Hawthorns.
A disjointed first half was lit up by the beacon of quality which was Sturridge's goal.
During the midweek Merseyside derby victory Suarez and Sturridge were falling out over who should pass to whom but there was no such disagreement here, with the in-form strikers were on the same wavelength.
The continually-improving Raheem Sterling was released through the inside-right channel and held the ball up long enough for Suarez to go round the outside of him to receive the pass.
Suarez's movement to generate space for the cross was brilliant and he picked out Sturridge at the far post for the England international to convert. He has now scored in 15 of 19 games this season - but even he paused before celebrating as he was not entirely sure whether he was onside.
There was little else in the way of chances with Suarez failing to properly plant his head on a Philippe Coutinho corner and then being denied the decisive touch on Aly Cissokho's cross by Jonas Olsson, who injured himself in the process and was replaced by Diego Lugano.
West Brom's first-half efforts amounted to Youssouf Mulumbu's drive, blocked by Steven Gerrard although it appeared to be going wide, and Zoltan Gera's shot which fizzed across goalkeeper Simon Mignolet and wide of the far post.
The home side came out with greater intent after the break and a period of early pressure resulted in Mignolet saving well from Gareth McAuley's powerful header.
It seemed apparent 1-0 would not be enough for Liverpool to hang on to and Suarez should have made it more comfortable when he brought down Toure's long ball, sidestepped compatriot Lugano, cut back inside but was denied by the outstretched leg of goalkeeper Ben Foster.
Mignolet made another good save, this time from Chris Brunt's low free-kick on the edge of the penalty area, but was helpless to prevent the equaliser.
Rodgers wants his side to play out from the back but Toure, unlike Agger, is not comfortable on the ball and inexplicably passed straight to Anichebe 20 yards out and the former Everton striker made the Ivory Coast defender pay dearly for his mistake.
Liverpool's switch to three at the back following the introduction of Martin Kelly and Joe Allen saw Sturridge denied by a charging Foster with Toure heading over Gerrard's resulting corner.
It was to prove the last real chance as Liverpool did not carve out enough openings for their potent strikeforce to benefit.