Bonjour Kathleen,

Yes, they are functioning as adjectival phrases. They can be inserted into a relative clause.

a "fish knife" with a flat blade = … which has a flat blade

un "couteau à poisson" à lame plate = ...qui a une lame plate

Answers with and without the article are correct here. They are accepted in the correct answers for this writing exercise.

The article can be omitted sometimes for stylistic reasons.

Examples:

Voltaire, célèbre auteur français, … = Voltaire, famous French author, …

Voltaire, un célèbre auteur français, … = Voltaire, a famous French author, … 

 

Ce couteau à lame tranchante … = this sharp edge knife, …

Ce couteau, à la lame tranchante, … = this knife, with a sharp edge, …

 

Ce scalpel à lame tranchante … = this sharp edge blade scalpel ...

Ce scalpel, à la lame tranchante ... = this scalpel, with a sharp edge, ...

 

I hope this is helpful.

Bonne journée!