The tool will allow publishers to put query boxes on their sites and also choose which sites Google indexes for the customized search engine. Publishers can choose to only include their own sites, or can expand the index to any sites in their industry--including sites operated by competitors.

Ultimately, however, the usefulness of the product will depend on the work that publishers put into crafting an index, search industry watchers said.

David Berkowitz, director of strategic planning for search engine marketing firm 360i, said that publishers might inadvertently create a search engine that has little to no utility for their users. "When it comes down to it, it's a great service that Google is offering, but it falls on the publishers to implement it well," he said. "It's very easy to implement this halfheartedly and create a disservice for your users."

Both having an engine that returns too many results and one that returns too few could lead the engine not to be useful, Berkowitz said. If it's too broad, then users have no reason to use the customized product instead of the general Google search, Berkowitz said. On the other hand, he said, "if it's too narrow, users might just want to go to other sites instead of using yours."

Greg Sterling, principal of Sterling Marketing Intelligence, said that with enough work, the service could yield better results than Google for users. "The richness of the experience will be directly correlated to how much work they put in," he said. "It potentially is much more relevant than general Web search. There's a lot more noise in general Web search."

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