Article 149 itself lists all the CAG's specific powers and duties.

It doesn't; it only says Parliament can prescribe them by law (which it did via the 1971 Act) and provides a fallback to pre-1950 practice until such a law exists.

The CAG's powers are frozen from 1950 and unchangeable.

Parliament can and did update the CAG's powers through legislation, most notably the CAG's (Duties, Powers and Conditions of Service) Act, 1971.

The Constitution of India

Article 149

Duties and powers of the Comptroller and Auditor-General

The Comptroller and Auditor-General shall perform such duties and exercise such powers in relation to the accounts of the Union and of the States and of any other authority or body as may be prescribed by or under any law made by Parliament and, until provision in that behalf is so made, shall perform such duties and exercise such powers in relation to the accounts of the Union and of the States as were conferred on or exercisable by the Auditor-General of India immediately before the commencement of this Constitution in relation to the accounts of the Dominion of India and of the Provinces respectively§

Why this exists

When the Constitution was adopted in 1950, India needed continuity in government auditing. Rather than leave a gap, the framers let the pre-independence Auditor-General's powers carry over automatically, while giving Parliament authority to update and formalize these powers later through legislation, which it eventually did via the CAG's (Duties, Powers and Conditions of Service) Act, 1971.

How courts read it

Courts have generally treated Article 149 as an enabling provision confirming that the CAG's audit powers are rooted in law, either the pre-1950 practice or the 1971 Act. Judicial discussion (e.g., in cases involving the CAG's authority to audit private companies or public-private partnerships) has focused on whether specific audit powers fall within what Parliament authorized under the 1971 Act, rather than reinterpreting Article 149 itself.

Common misconceptions

Myth: Article 149 itself lists all the CAG's specific powers and duties.
Fact: It doesn't; it only says Parliament can prescribe them by law (which it did via the 1971 Act) and provides a fallback to pre-1950 practice until such a law exists.
Myth: The CAG's powers are frozen from 1950 and unchangeable.
Fact: Parliament can and did update the CAG's powers through legislation, most notably the CAG's (Duties, Powers and Conditions of Service) Act, 1971.