The agency's responsibility once you contact them, particularly in the context of a debt collection agency, includes providing you with a written notice within five days of their first contact. This notice must include the amount of the debt, the name of the original creditor, a statement of your right to dispute the debt, and what will happen if you do or do not dispute it within a certain timeframe. The agency must also identify themselves clearly, not harass you, and respect your rights to privacy and reasonable contact times. They are obligated to verify the debt if you dispute it in writing within 30 days and must comply with these guidelines under laws such as the Fair Debt Collection Practices Act (FDCPA).