Is the marriage contract considered valid if the mufti does not explicitly ask the bride and groom for their consent, and is the phrase "I agree" from both parties sufficient for offer and acceptance?

The offer is for the woman's guardian to say: "I marry you to so-and-so," or "I give so-and-so to you in marriage." The acceptance is for the husband to say: "I accept her marriage," or "I accept her matrimony," or "I consent to her marriage." It is not a condition for the two wordings to be identical. It is permissible for the husband's wording to precede the guardian's wording. Whenever the offer and acceptance are made, and two just witnesses attest to them, the marriage is valid. The presence of a judge or a mufti (definition) is not a condition for performing the contract. The consent of a previously married woman (thayyib) is a condition.