Isn't there suggestions for attribute's values or a way to know which values are accepted? [VS CODE]

Isn't there any way for the intellisense suggestions to know the accepted values for the attributes in a simple and easy way while coding?

I'm a newbie, and I think that'd kill my productivity if I had to look over all the docs to find the options trying to implements some traits from some external library.

I'm using clap lib.

I'm doing:
#[clap(short, long, value_parser)], but I actually want to know which values can I put into #[clap(<here>,...)] from inside my IDE instead of crawling their docs.

Not really: Allow proc macros to expose their grammar to rust analyzer for syntax error understanding · Issue #7402 · rust-lang/rust-analyzer · GitHub.