The Adverb TOO denotes some kind of excess. It means more than enough, something that goes beyond the contemplated limit or purpose. All such sentences as the following, where TOO has been wrongly written for VERY make sheer nonsense.
My son's health has been too good.
Sugar is too sweet.
I am too happy to see you again.
He writes too neatly and spells too accurately.
The milk of a cow is too nutritious.
The water of this river is too pure.
The roof of this house is too strong.
But TOO is used correctly in the following sentences.
1. Her heart was too full for words.
2. This news is too good to be true.
3. He is too old to work hard.
Such sentences as (I shall be too pleased to help you.) are accepted in colloquial or familiar style. But they should be avoided in more formal English.