If you're Githzerai or have the Telepathy feat, are spell components required for the spell-slot-powered castings?

Question

The typical concept of innate telepathy is that you just have to "think at something" in a certain way and it happens. You're not casting a spell and using magic, so you don't expect the process to require verbal, somatic, or material components in the way spells do. It just happens.

However, D&D 5e does use spells to describe the inherent mechanics, so, to match the fantasy, it will generally indicate that spell components aren't required. However, there's some confusion when you're using spell slots to power castings.

For example, the final bullet point of the Telepathic feat in Tasha's Cauldron of Everything says:

You can cast the detect thoughts spell, requiring no spell slot or components, and you must finish a long rest before you can cast it this way again. [...] If you have spell slots of 2nd level or higher, you can cast this spell with them.

Similarly, the Githzerai description in Mordenkainen Presents: Monsters of the Multiverse includes the following:

[...] Once you cast shield or detect thoughts with this trait, you can’t cast that spell with it again until you finish a long rest. You can also cast either of those spells using any spell slots you have of the appropriate level.

[...] None of these spells require spell components when you cast them with this trait.

My initial interpretation was that spell components were not required when the spells from these features were re-cast. A spell slot was needed to provide the fuel, yes, but the telepathy was still telepathy, so the character didn't suddenly need to speak gibberish and wave their hands about like a wizard. However, reexamining these descriptions has made me worry that this interpretation does not match the rules as written.

Does the character need to have spell components for the castings that are powered by spell slots? Does the "psionic flavor" vanish after the first casting?

Answer 1

The Githzerai does need components when casting with spell slots

[…] Once you cast shield or detect thoughts with this trait, you can’t cast that spell with it again until you finish a long rest. You can also cast either of those spells using any spell slots you have of the appropriate level.

[…] None of these spells require spell components when you cast them with this trait.

The feature provides you with two ways of casting these two spells - with the trait itself or with a spell slot. It doesn't require components only when you cast it with the trait and you can do that once per long rest. If you cast the spell with spell slots, you need components as normal.

The feat works in the same way, it gives you a specific option to cast the spell without needing components or spell slots. It does allow you to use your own spell slots too but then these don't apply, you're casting as normal and need any components the spell requires.

Answer 2

A Githzerai needs spell components when these spells are fueled by spell slots.

You quoted the relevant rule (emphasis mine):

None of these spells require spell components when you cast them with this trait.

When you cast Shield or Detect Thoughts using the Githzerai Psionics you do not need components.

The other part of the description of the trait states that you can cast one of these spells once per long rest. The reading of the second sentence

You can also cast either of those spells using any spell slots you have of the appropriate level.

specifies that when you used this trait, you can still cast these spells using one of your spell slots (if available). Since you are not using this trait but your spell casting ability, you have to follow the usual rules for spell casting, hence if the spell requires verbal, somatic or material component you must satisfy this constraint.

A character with the Telepathy feat needs components when fueling Detect Thoughts via spell slots.

The description reported of the feat says (emphasis mine):

You can cast the detect thoughts spell, requiring no spell slot or components, and you must finish a long rest before you can cast it this way again. Your spellcasting ability for the spell is the ability increased by this feat. If you have spell slots of 2nd level or higher, you can cast this spell with them.

The highlighted part tells that once you cast Detect Thoughts without using spell slots or components, you must finish a long rest for doing it again in this way, i.e. without using slots or components. Otherwise, if you have spell slots you can use them, but unless you have some particular feature (for example, the Sorcerer's Subtle Spell metamagic option) you have to follow the normal spell casting rules.