Making sense

it should rearrange words into a plausible sentence when it can, using knowledge of verbs, nouns and common sentence structures.

Not aiming for perfection here, just simple sentences.

There are some examples and background on the theory here http://www.writingcentre.uottawa.ca/hypergrammar/sntstrct.html

There might be modifiers that make things plural or adjust other bits.

I want the teddy

I want to play with the teddy

I want the brown teddy

I want to play with the brown teddy

I want to play with the big brown teddies

I want an apple

I want a green apple (note a not an)

Please can I have a green apple (polite modifier changes the structure)

I want a green apple please (polite modifier with a simpler but less natural structure)

time and tense

I want an apple (future, desire)

I had an apple (past)

I have an apple (present)

When can I have an apple? (question, unknown time)

(WW: this to me sounds a little like a Automatic Conjugation algorithm. This might be useful Ultralingua have a product with an API I understand you could use.. at a cost!)