Note that another, perhaps safer, way of capturing everything after "agent_id=>" up to but not including a comma is to use use a negated character class ([^,]+) meaning one or more of anything that isn't a comma rather than a non-greedy match of anything (.+?). You can also populate your array, let's call it @agents, in one fell swoop by using a global match (g flag) and a map within which we substitute away the double-quotes.

$ perl -Mstrict -Mwarnings -MData::Dumper -e '
> my $line =
>    q{xxx:agent_id=>foo,yyy:agent_id=>b"a"r,zzz:agent_id=>"baz",qqq};
> 
> my @agents =
>    map { s{"}{}g; $_ }
>    $line =~ m{ :agent_id=> ( [^,]+ ) }xg;
> 
> print Data::Dumper->Dumpxs( [ \ @agents ], [ qw{ *agents } ] );'
@agents = (
            'foo',
            'bar',
            'baz'
          );
$
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I hope this is helpful.