What are the maximum number of values that can be added per slot when creating a skill in Alexa?
It looks like the AMAZON.LITERAL was deprecated due to concerns around skills recording raw user conversations as an input.
I've got a large number of possible values that could be used as an input if users raw input cannot be recorded.
"A skill can have a total of 50,000 custom slot values, totaled [sic] across all custom slots used in the interaction model."
https://developer.amazon.com/public/solutions/alexa/alexa-skills-kit/docs/alexa-skills-kit-interaction-model-reference#h2_custom_syntax
This limit (and the lack of any ability to change them on the fly) is certainly a limitation that comes up. On the other hand, keep in mind that the word list is just a guide to how Alexa should interpret user input, so the total number of possible inputs is actually much greater then 50K.
For more, you might want to read this article:
Why a Custom Slot is the Literal Solution https://developer.amazon.com/blogs/post/Tx3IHSFQSUF3RQP/Why-a-Custom-Slot-is-the-Literal-Solution