Say vs.tell

Which sentence below is correct?

(a) What do you [size=150]say[/size] about the following sentence?

(b) What do you [size=150]tell[/size] about the following sentence?

(b) does not seem very likely (“what can you tell” would be more usual). (a) is possible, but it may not be the most natural question to ask in the scenario you have in mind. More information is needed about the context.

Dozy,

  1. Did she tell/(X: say) you her name?
  2. Tell/(X: say) me (all) about (it)/(your story).
    We can’t use ‘say’ in these sentences.
    Am I correct?

The first difference between the two words is that ‘to tell’ is transitive, and takes a direct object:
[color=indigo]He told me all about…
He told us how…

We couldn’t use ‘to say’ here. ‘to say’ takes an indirect object:
[color=indigo]That’s not what he told us. He told us that…
That’s not what he said to her. He said (to her) that…

Secondly, ‘to say’ has the sense of simply passing on information, whereas ‘to tell’ has the sense of intent on the part of the speaker when imparting information.
[color=indigo]I told her and told her, “Little Red”, I said. “Don’t go into the wood”, I said. “Red Riding Hood - don’t go into the wood!” But does a teenager listen to her parents these days?"

Can others refine my thinking?

I hate to be so nitpicking but this is not exactly right.
“To tell” CAN be transitive, but it can be intransitive too.

thefreedictionary.com/tell

  1. Did she tell you her name?
    Did she say her name?
    Did she say what her name was?
    Did she tell you what her name was?

  2. Tell me about it.

  1. Did she tell you her name?
    Did she say her name?
    Did she say what her name was?
    Did she tell you what her name was?

  2. Tell me about it.