Tone
Toaq is a tonal language. It has tones! That is: saying a word with a rising or falling vocal intonation, for example, makes for a difference in meaning.
Function of tones
Toaq has grammatical tone: when you change the tone of a word, its grammatical function changes (for example dẻ “is beautiful” → dẽ “beautifully”).
(This is in contrast to lexical tone, like in Chinese: there, when you change the tone of a syllable, it becomes a different word (lexeme) entirely. For example 西 xı̄ “west” → 媳 xí “daughter-in-law”.)
Verb tones
Every verb can be "conjugated" into one of six tones, each of which expresses some grammatical function:
- (see History section for why there is no tone #1)
- The rising tone
marks a noun or bound variable. (súq “you”, sa pỏq… póq “some person… that person”) - The rising-creaky tone
marks the start of a relative clause. (gï “which is good”) - The falling tone
marks a verb phrase, or the tail of a serial. (fả “goes”, bũ dẻ “not-beautifully”) - The rising-falling tone
marks the start of a content clause. (gî “that it's good”) - The mid-falling tone
marks a preposition. (bìe ní “after that”) - The falling creaky tone
marks an adverb. (dẽ “beautifully”)
Sometimes people will say “the fifth tone” or “t5” instead of “the rising-falling tone”.
Neutral tone
Particles, on the other hand, are in the neutral tone 
(aka the 8th tone), which is not really a tone. The only rule is that you don't continue the contour of the previous tone. So, when saying a particle after the falling tone , you should go up in pitch to break the falling contour. This way, the listener can tell the difference between lẻ moq and lẻmoq.
Lexical tone
Toaq actually does have a little bit of lexical tone. For example, moq (question marker) and môq (rhetorical question marker) are different lexemes.
More subtly, lâ is not + lả. Rather, each of and lả is a complementizer in its own right. So really lâ is also its own complementizer, of which is an allomorph.
History
There used to be a flat tone 
, which marked the continuation of a multisyllable word. But now, the tone contour is spread out over the whole word. This was tone #1, but now it is gone. So we start counting from #2, because it would be more confusing to re-number them.
The rising-creaky tone used to be dipping 
, and was just “creaky”.