There is no way to set the resulting out name for a static library artifact.
If I call mbed compile -t GCC_ARM -m K64F --library --artificat-name my-lib-name
I get the following error:
build.py: error: no such option: --artifact-name
This issue was solved in mbed-os tools:
ARMmbed/mbed-os#1955
But wasn't exported to mbed-cli.