Working with his friend and colleague - Alessandro Costa - the site began by carrying out fact-checking on a local scale, during the mayoral elections in Genoa last year, running from March until the end of May. With the experience under their belt, the team expanded to a national perspective in October, in time to cover the run up to the 2013 general election.
The site faces a number of challenges, from finding a sustainable business model which will support their editorial independence to dealing with the backlash from political supporters. But Agnoletto is hopeful that the work will have a positive impact, not only on journalists and their approaches to political reporting, but also the citizen's understanding of politics and the responsibility of the politician's themselves, when it comes to the dissemination of accurate information.
The fact-checking process
Politicometro uses a thermometer system to illustrate the result of its fact-checking, ranging from 'balla colossale' (terribly false) to 'vero' (true), with three other levels of factual accuracy in-between.
The ability to fact-check a statement made by a politician is based on whether or not there is relevant data for the team to refer to, Agnoletto told Journalism.co.uk. "We can check only the declarations with data and some numbers [to back it up]," he said.
And the time it takes varies. In some cases, it can take days to "check one sentence", whereas in others it can be more immediate where the data is available. It might also be that the politician is expected to comment on a recent data release, in which case the information can already be to hand ahead of the politician's comment on the matter, and checked almost in real-time if made on television, for example.
Politicometro carries out 'live' fact-checking each day, at the same time as politicians appear on television talk-shows. As well as reporting its findings on its website, it also does so in real-time on Twitter and Facebook.
Where the team cannot find the relevant data, they will try to ask the politician, or their staff, where the data they referred to originated from. But Agnoletto said they rarely get an answer.
The funding challenge
Politicometro is produced by a team of around 10 people, who all work voluntarily from across Italy. Agnoletto said that he is contacted on a weekly basis by people asking to get involved. But financing the project, and therefore being able to pay those people, "is a big problem", he said.
He is not prepared to accept funding unless the site's "total independence" can be guaranteed. And a crowdfunding campaign last year brought in just €50 - "enough for four pizzas".
In a bid to find a solution, the team are currently "looking for someone who can work to find a way for us to make money with total independence", he said.
This problem is not limited to Politicometro. Other fact-checking sites which Journalism.co.uk has spoken to before have also referred to the difficulty of finding funding as non-profits, with grants usually a key source in the end.
Fact-checking in the mainstream
Looking across mainstream media, Agnoletto recognised signs that fact-checking is placing an increasing role in political journalism.
During the general election this year, "some media tried to be innovative and use fact-checking", he said, adding that Sky TV, for example, "made some programmes with a candidate and used fact-checking to check what they were saying".
He added that Turin-based newspaper La Stampa also used "fact-checkers and articles about what candidates were saying" in its political coverage.
"But, except these two or three cases, nobody has tried to do something new, to improve the situation of Italian information," he said.
More generally, he argued that when it comes to subjects such as open data and transparency, Italy is behind the times.
"We are trying to adapt to your UK model, the American model, but we are in the Victorian age," he said, adding that the relationship between some parts of the media and politicians can make it "very difficult".
Likening the situation to the two sides of a football match, "it is based on what is your favourite team, and not who is the best, who is wrong", he said.When we say something is true, we are the best news website in Italy, when we say something is false, we are the worst, paid, corrupted news website in ItalyMatteo Agnoletto, Politicometro
And it can receive strong reactions to its findings on social media, he said, by political supporters. If a statement is said to be false, for example, Politicometro has been accused of being influenced in some way by the opposing party.
"Everybody thinks that we do this work with another aim, a political aim, so it's difficult," Agnoletto said. "When we say something is true, we are the best news website in Italy, when we say something is false, we are the worst, paid, corrupted news website in Italy".
Working with other media
When it comes to the potential to collaborate with other media outlets in the future, or at least introduce similar practices within a news outlet, Agnoletto sees potential in broadcast media. In the week we spoke to him, for example, he said he was asked to appear on national television to discuss fact-checking on two occasions.
And in the site's earlier days, he would work with local media outlets each week, and so is not "closed to the other media", he said.
But in terms of the nature of fact-checking, he does feel that the most effective link up would be with broadcasters, to improve the way politicians are held to account during on-air interviews.
Instead of political interviews going viral because they turn into an on-air "fight", integrating fact-checking into those interviews could help the viewer better understand the politics at hand, he said.
And overall, Agnoletto hopes that as well as improving the way journalists and politicians think about fact-checking, it will serve to better inform citizens at the ballot box.
"If I receive good information, and information that isn't like a football match, I can better understand all the situations surrounding me, the political situation in Italy.
"I think then, when I have to vote on election day, I am really prepared and know what the candidates want for my future, for our future."
- This feature is the latest in a series putting the spotlight on Italian media, following Journalism.co.uk's recent visit to Rome. We have also reported on how L'Huffington Post liaises with other editions of the site across the world, and more coverage is to follow soon.