Most of the 15 exchanges run by states and the District of Columbia do not have provider directories or search tools on their Web sites — at least not yet — so customers cannot easily check which doctors and hospitals are included in a particular plan’s network. Most allow customers to search for providers by linking to the insurers’ Web sites, but the information is not always accurate or easy to navigate, health care experts say.

At this stage, even many doctors are uncertain about whether they are contracted with exchange plans from state to state because the plans — and even some of the insurers — are so new.

“I’ve had to do all this legwork on my own,” Mr. Wheeler said. …

Exchange officials say they plan to make it easier for customers to see which providers and drugs are covered as they continue to refine the new Web sites. But for now, a lack of quick and easy search tools is adding another layer of frustration in the opening weeks of a program that has been plagued by technological problems and political attacks.