I don't know about tools specifically for medical students, but there are a lot of scales for metacognition that could be adapted, like this one:

Schraw, G. & Dennison, R.S. (1994). Assessing metacognitive awareness. Contemporary Educational Psychology, 19, 460-475.

Here is a good basic resource on metacognition from Vanderbilt University:

https://cft.vanderbilt.edu/guides-sub-pages/metacognition/

The reference list at the end has a ton of sources with assessments and studies on metacognition.

I found this article through Bing about assessing metacognition in a physiology course that may be helpful:

Garrett, J., Alman, M., Gardner, S., & Born, C. (2007). Assessing Students’ Metacognitive Skills. American Journal of Pharmaceutical Education, 71(1), 14.

Great thanks Alisha

What is mean with "skill"? To give an injection in vein or muscle? Or is meant how to learn physology for the intermediate examination?

Dear Dr. Retter,

Thanks for your reply. Studying skills for medical students means ( in my question): ways, tools, tips, making and using notes, time management , schedule, organization and test strategies. All these methods that medical students can use in studying, How can I evaluate them? Can I design a questionnaire? or there is a valid standard method to use.