Facebook launched a new search tool for its social network amid much fanfare last night, but the firm was tightlipped on how the service would work across mobile devices or when it would be integrated into its mobile apps.

Unveiling ‘Graph Search’ at an event in San Francisco last night, Facebook CEO Mark Zuckerberg described the new tool as the “third pillar” in the Facebook proposition alongside ‘News Feed’ and ‘Timeline.’

Graph Search will allow Facebook users to combine phrases (for example: “my friends in New York who like Jay-Z”) to return people, places, photos or other content that’s been shared on the social network.

Zuckerberg was keen not to position Graph Search as a competitor to Google’s market-leading search engine, even though it is integrated with Google rival Bing to cover searching outside of the Facebook sphere.

“I don’t think people will come to Facebook to do web search. That isn’t the intent of this,” he said.

The service is launching initially as a limited beta mode on Facebook’s desktop site. Zuckerberg said that work is already underway on integrating Graph Search on the mobile side, but added that it was “hard for us to estimate” how long this would take.

But some commentators believe that Graph Search has the potential to make a big impact when it launches on mobile.

“This is far more important for Facebook’s mobile strategy than simply doing a Facebook phone,” said Victor Basta, managing director of Magister Advisors. “Graph Search will be key to generating revenues from Facebook’s hundreds of millions of mobile users through super-value, highly targeted search. To date it has been very difficult to serve up advertising on a small screen.  Search is really the only way to do it.”