From the Vademecum:
The evaluation of each received STSM application is performed by the Action MC. The (...) Committee can assume this responsibility if the Action MC gives them the mandate to perform this task on their behalf. The evaluation criteria dfined by the Action MC should be communicated to all potential applicants.
The selection of successful STSM applicants must be done so in consideration of the scientfic scope of the proposed mission and how the mission can support the Action in achieving its scientfic objectives. There should be special considerations made by the Action MC with respect to supporting COST policies on promoting gender balance, enabling Early Career Investigators (ECI), broadening geographical inclusiveness.
Proposals will be evaluated for their quality and for their relevance to ERNEST objectives. Proposals will be evaluated by a committee composed of the STSM Coordinator, the Action Chair and the Action Vice-Chair.
In case of conflicts of interest, the evaluation committee member(s) involved will be replaced by the Equality and Inclusiveness officer. The evaluation committee will also confer with the Equality and Inclusiveness officer regarding the fair distribution of the STSMs across research groups, countries, and genders.
For this reason, it is unlikely that more than one proposal by a single applicant will be accepted during one Grant Period. The amount granted will be based on the budget requested by the applicant, as well as the funds available for STSMs in the overall ERNEST budget.
Since longer STSMs are more likely to be associated with higher costs,
the duration of the STSM will also be considered when deciding the granted support. The evaluation committee will provide (brief) feedback about the evaluation to the applicants.