As long as a debt collector does not fudge the facts of the debt - claiming, for example, that the debt itself is $700 rather than $200 debt + $500 attorney costs - the debt collector is not violating the FDCPA, this if the collector is allowed under the original contract and/or state law to collect interest, fees or other charges in addition to the original debt.
Sorry, but your "example" won't fly.
The reason it won't work is because your $700 figure includes elements of potential debts (attorney fees and costs) that can only be predicted and are not due and payable unless and until ascertained and awarded by a court of law. In other words, the $700 is not presently due and owing and hence a fictitious figure serving as the "the amount of debt"! Language which is the gravamen of the legislation.
Any pre-judgment indication by the collector to the often guileless debtor that such prophesized figures which have yet to accrue but are alleged to constitute "the amount of the debt" inferring that they are presently due and owing is one of the shady practices that the FDCPA is designed to curtail and hence it is violation of 15 USC 1692g to represent them as being a current obligation!
Analogous is Veach v. Sheeks, 316 F.3d 690 (7th Cir. 2002). There the attorney bill collector Sheeks did precisely what you propose. His validation letter incorporated penalties and fees as obligations presently due and payable. The 7th Circuit Court awarded judgment in favor of the debtor Veach concluding that by stating the amount of the debt as $1,050, Sheeks took it upon himself to hold Veach liable for penalties that had not yet been awarded stating:
"The "amount of the debt" provision (1692g (a)(1) is designed to inform the debtor (who, remember, has a low level of sophistication) of what the obligation is, not what the final, worst-case scenario could be."
Also is Bernstein v. Howe, 2003 U.S. Dist. LEXIS 5284 (S.D. Ind.)
"The Bernstein court concluded that no attorney’s fees were actually owed by Bernstein at the time Howe sent his letter. At most, the credit card agreement provided the potential for a future award of attorney’s fees in the event that First Card incurred attorney’s fees as a result of pursuing "legal proceedings" against the debtor. Relying on Veach, the court held that a debt collector violates the FDCPA by representing that potential for fees as a part of the debt owed." (Emphasis added)