They could be either descriptions or links to wiki entries
for instance
spell_effect_values
This table is for this and that
id: (int) unique id
To distinguish effects from each other
type: (int) spell_effect_types unique id
This is what the spell will do
and so on
oh btw i've just noticed
spell_effect_values.type is smallint but should be at least the same as spell_effect_types.id == int
better would be the id of a list of effects for that particualar spell

In the wiki sounds better, then it is searchable. Get to work!

Aye, adding comments to databases is for noobs. But I do like the Wiki idea. Detail out the DB schema with descriptions there. Community supported. I'm all for that.
Remember: DB schema is still changing, and will change for some time. Do not get to ahead of yourself, since table names and purpose will likely change.