It's important to handle exceptions in your service. When developing the service, you can set the WCF to provide more detailed information, adding this tag to configuration file, usually Web.config:
<serviceDebug includeExceptionDetailInFaults="true"/>
This tag must be placed within the serviceBehavior tag, usually like this:
<system.serviceModel>
<behaviors>
<serviceBehaviors>
<behavior>
<serviceDebug includeExceptionDetailInFaults="true"/>
</behavior>
</serviceBehaviors>
</behaviors>
</system.serviceModel>
Example of detailed infomation:
Server stack trace: em System.ServiceModel.Channels.ServiceChannel.HandleReply(ProxyOperationRuntime operation, ProxyRpc& rpc) em System.ServiceModel.Channels.ServiceChannel.Call(String action, Boolean oneway, ProxyOperationRuntime operation, Object[] ins, Object[] outs, TimeSpan timeout) em System.ServiceModel.Channels.ServiceChannelProxy.InvokeService(IMethodCallMessage methodCall, ProxyOperationRuntime operation) em System.ServiceModel.Channels.ServiceChannelProxy.Invoke(IMessage message)
Exception rethrown at [0]: em System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg) em System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type) em IMyService.GetDataOperation(RequestObterBeneficiario request) em MyServiceClient.GetDataOpration(RequestData request)
This will return to the client detailed information. During development this can help out, but when your service goes to production, you will no longer keep this because your service can send sensitive data, like your database name or configuration.