Returns a Medicare Advantage contract's CMS Star Ratings: the Overall, Part C, and Part D summary stars for a rating year, each with the year-over-year change vs the prior year. Set include_measures=true to also get the full per-measure breakdown (measure name, identity key, part, domain, weight, direction, the raw value and its star, the 4-star line, and the star's YoY change) so you can see exactly which measures moved the rating. The prior-year star is matched by MEASURE IDENTITY through the Stars measure spine, never by code (CMS renumbered 27 of 33 Part C codes for RY2026); prior_year_measure_id names the code the prior star was filed under. Filter by contract_id (required) + optional year (the rating_year, defaults to the latest) + optional limit (max measure rows returned). Rating years 2012-2027 (RY2027 is CMS's final October 2026 release). The answer is a detail payload: the headline stars sit in value.summary, the part rows in value.summary_parts, the measure rows in value.measures.

Stars drive the quality-bonus payment and rebate, so this sits directly upstream of the plan economics (payment and MLR) and is reported at the CONTRACT level (no plan_id).

Scores are served at the precision CMS publishes (float32 storage noise is removed on the wire). Each measure row's four_star_ladder names the cut point ladder its four-star line came from: CMS calculates MA-PD and PDP Part D cut points separately, so an MA contract (H, R) reads the MA-PD ladder and a stand-alone drug plan contract (S) the PDP ladder; ALL is a ladder CMS published for every organisation (Part C).

RESTATED OVERALL. CMS restated 50 contracts' RY2026 Overall rating on July 22, 2026 (after the Clover Health ruling) without changing any measure star, so for those contracts the measure breakdown reflects the original calculation and can round to a different star than the served Overall. The answer says so in a caveat and names the original value in summary.overall_restated_from (summary.overall_restated_from_text carries CMS's text when the original was a message such as 'Not enough data available').

SOURCE: CMS Star Ratings (summary + measure-level) and the Vlada measure spine medicare_semantic.dim_stars_measure_identity_v6.