Caffeine plus L-theanine, at the doses that were actually studied

The paper people mean

Haskell 2008 used about 97 mg L-theanine with a modest caffeine dose and saw cleaner attention than caffeine alone. That ratio is the reference, not a vibe.

A typical matcha serving might give 50–90 mg caffeine and 20–40 mg theanine. You get the pairing for free. You do not get the capsule milligrams unless the label says so.

When tea is enough

If the job is ‘a bowl that is less jagged than espresso’, matcha is a rational tool. If the job is ‘replicate Haskell’, buy assayed theanine and counted caffeine — or admit you are not replicating Haskell.