Why can the 1935 agreement with France on mutual assistance in the event of an attack by an aggressor

Why can the 1935 agreement with France on mutual assistance in the event of an attack by an aggressor be considered ineffective?

The agreement was concluded, but clarification was required on the practical component. How exactly this mutual assistance will be carried out. Therefore, an additional agreement was required. But Laval, constantly postponed this decision until later. In 1939, there was a discussion of an agreement on practical measures, but the parties did not come to a mutual agreement. Therefore, the agreement turned out to be completely ineffective.