Does sending a message mean we have an agreement?
In short: No. A message starts a conversation, not an engagement. Work begins only after I send a written scope and quote by email and you sign the engagement letter.
You can ask anything without committing to anything. Until the engagement letter is signed, you owe nothing and I have not started work.
The line matters for both of us. It means you always see the fee and the scope in writing before you decide, and it means nothing I say in a quick message can be mistaken for a professional opinion. The engagement terms set this out as section 1.