Capabilities

Capability	Description	Values
app	The absolute local path to an .xap file to be installed and launched. Note that this capability is not required if debugConnectToRunningApp is specified.	C:\test\app.xap
files	Dictionary. Each key of the dictionary is "local file path", each corresponding value is "remote file path".	e.g., { 'C:\AppFiles\downloadedPicture.png': 'download\picture.png' }
deviceName	Name of emulator to use for running test. Note that this capability is not required, if no device name is specified, then a default emulator is used.You can specify only partial name, first emulator that starts with specified deviceName will be selected.	e.g., Emulator 8.1 WVGA 4 inch 512MB
innerPort	Inner driver port used to communicate between OuterDriver and InnerDrive (injected into Windows Phone app). Note: Required only if non-default port was specified in tested app in AutomationServer.Instance.InitializeAndStart call.	e.g., 9998 (default)
launchTimeout	Maximum timeout in milliseconds, to be waited for application to launch (application is pinged every 0.5 sec).	e.g. 10000 (default)
launchDelay	Launch delay in milliseconds, to be waited to let visuals to initialize after application launched (after successful ping or timeout). Note: use it if the system running emulator is slow.	e.g. 0 (default)
platformName	Ignored in desired capabilities. Set to WindowsPhone in actual capabilities.	WindowsPhone
debugConnectToRunningApp	If true, then application deployment and launching steps are skipped. Driver assumes that emulator (specified by deviceName) is already running and application is launched.	true or false

You can obtain list of installed emulators by running: "C:\Program Files (x86)\Microsoft SDKs\Windows Phone\v8.1\Tools\AppDeploy\AppDeployCmd.exe" /EnumerateDevices