How much disk space do the "command line developer tools" take up?
The installer says it requires 2.72 Gb of space. It installs a variety of Unix tools for compiling software, and other advanced usage (such as git) on the command line, including 'many other useful commands that are usually found in default linux installations' (osxdaily.com). It also includes the SDK frameworks and header files for macOS APIs. And python3.
Separating out what it is exactly that you need and what you don't is not really feasible, and may cause errors. Presumably, you're doing some kind of scripting/programming, for which other tools in the CLDT might be useful.