We already have other similar implementation lined up. There's @pure-unless-callable-is-impure which is implemented in the parser (#253) but not yet in PHPStan (phpstan/phpstan-src#3482).

It's not a great look when there's a tag understood by the parser but not by the analyser. I'd like to minimize that coming into the future. It'd be nice to also have the implementation ready in phpstan-src before merging the parser countepart.

I will look at this again when phpstan/phpstan-src#3482 is merged and the implementation for @pure-unless-parameter-passed is ready in phpstan-src.