Mode
Enter an octal mode (755, 4755), a symbolic string (rwxr-xr-x or -rwsr-xr-x), or a chmod expression (u+x,g-w,o=, a+rX, g=u). An expression is applied to the starting mode you give. X sets execute only on directories or files that already have an execute bit. A clause without u, g, o or a is filtered by the umask, as chmod does.
Umask
New files start from 666 and directories from 777, and the umask clears bits from that. Executable bits are never set on new files.
Sudoers
Paste a sudoers file or a drop-in from /etc/sudoers.d. Each rule, alias and Defaults line is explained, and the linter flags rules that grant more than they appear to: ALL commands, NOPASSWD, wildcards, programs that can open a shell, negated commands, missing absolute paths and writable locations.
This is a static check and it does not run sudo. Always edit with visudo and validate with visudo -c -f file, because a syntax error in sudoers can lock you out of sudo.