Scotland's first private prison has been criticised by inspectors for the "limited" activities provided for inmates.
HM Chief Inspector of Prisons Brigadier Hugh Monro has now called for improvements in the work and education programmes at HMP Kilmarnock.
He also called for the overall standard of healthcare at the facility to be reviewed.
The latest inspection report claimed out-of-cell activities at the jail were "limited and lack stimulation".
It said "too few prisoners" attended the workshops, and that "too few prisoners also attend education and the educational facility is under-utilised".
The report complained that "large numbers of prisoners are not engaged in purposeful activity".
It also stated that access to activities was not good enough, with only 40% of prisoners out of the house blocks during the day.
Just 200 prisoners were taking part in work during the latest inspection, and Brig Monro said: "I was not satisfied that the quality of work was sufficiently good. In some workshops some prisoners have no work to do and spend much of the time drinking tea or watching other prisoners who do have work allocated to them."
Brig Monro recommended that access to work, vocational training and education at the jail is improved, and the quality of education and work should also be better.
The report described the education programme as "limited and under-developed".
It added: "Low numbers of prisoners access education programmes. A total of 139 prisoners out of a prison population of approximately 640 regularly attend education classes. This represents only 22% of the prison population."
Brig Monro accepted there were "good points in the prison's healthcare provision, not least the mental health area, smoking cessation, dental treatment and alcohol programme".
However, he said in the report: "I have serious concerns about many aspects of healthcare access, treatment, management and addictions work. Prisoners are very agitated about this whole area."
When the inspection was carried out, 215 prisoners at the jail were being prescribed the heroin substitute methadone.
But the report said there was "currently no means of assessing prisoners' compliance" with the methadone programme.
To address this it recommended a system be brought in immediately, for all prisoners on methadone to be tested regularly.
Brig Monro said he expected changes being brought in at the prison, together with the recommendations in the report, would "deliver improvements in many of the areas that this report highlights".
He went on: "Overall, Kilmarnock has a good and enthusiastic team who work very hard to deliver the services required by the Scottish Prison Service."
Justice Secretary Kenny MacAskill said the report showed Kilmarnock Prison was "operating safely through good relationships between staff and prisoners".
He said: "The Inspector has praised the mental health and alcohol programmes run at HMP Kilmarnock. Areas for improvement include out-of-cell activities and access to healthcare. I am confident that the Scottish Prison Service is well placed to respond to the points raised."