SQL Agent Jobs - What Permissions Required
SQLAgentUserRole allows users to create jobs and to manage jobs that they create. 

The SQLAgentOperatorRole allows users all the rights assigned to the SQLAgentReaderRole along with the permissions necessary to execute local jobs that they do not own.

Member of SQLAgentReaderRole role allow the user to see any SQL Agent job located on the server instance, even the jobs in which that user does not own. The user can see the job, along with any history saved to the job. However, the group is not allowed to execute the jobs