Depends on your definition of "small". Clap will add significantly to the compile time, but your binary won't be too much larger. Rust binaries tend to fall in the range of 2–30MB, depending on lots of things.

But that's still relatively small compared to Go, or even Python if you consider needing to bundle the interpreter for "fully statically linked".

clap adds about 300kb with my usual release mode profile (lto = true, opt-level = 'z', panic = 'abort', strip = true). Bigger than I would like but for most projects I'm OK taking the binary size hit for nicer ergonomics and more features than argh.