The body is code- and table-forward (anomaly catalog, isolation matrix, harness, per-DB matrix) with no rambling on concepts Claude already knows; "The Steps 4-6 workloads use time.sleep(0.5) ... can flake on slow CI" adds only the non-obvious timing caveat. It earns its tokens rather than padding, fitting the 'lean and efficient' anchor and not the 'mostly efficient but could be tightened' bar (2).

Real executable psycopg code with concrete assertions is provided throughout (two_connection_test harness, non-repeatable-read, phantom, write-skew, serializable tests, retry helper); the substantive logic is copy-paste ready. Undefined fixtures (setup_balance, setup_doctors, count_on_call) and one stubbed retry test are minor gaps that do not drop it to the pseudocode/missing-key-details bar (2).

Steps 1-9 are clearly sequenced (catalog -> matrix -> harness -> per-anomaly tests -> per-DB -> retry), with assert-based validation in each test and an explicit retry feedback loop (Step 9) plus a deterministic-variant note for flake recovery; anti-patterns and limitations act as checklists, matching the 'clear sequence with explicit validation steps; feedback loops' anchor rather than missing checkpoints (2).

The file is well-organized by section but entirely monolithic: the anomaly catalog, isolation matrix, full test library, per-DB table, and retry pattern are all inline in a single ~290-line SKILL.md with no split-out reference files (no references/ bundle exists). This fits 'content that should be separate is inline' (2) rather than the well-signaled one-level-deep references of the 3 anchor.

"Build per-database MVCC isolation-level tests" and "verify which anomalies are prevented at each level" list multiple concrete actions (build tests, verify anomaly prevention) and enumerate specific anomalies and four databases, matching the 'lists multiple specific concrete actions' anchor; it is not merely naming a domain (2) and goes well beyond vague language (1).

It clearly states what ("Build ... tests", "verify which anomalies are prevented") and an explicit when clause ("Use when two concurrent transactions can touch the same rows ... or before changing a service's default isolation level"), satisfying the 'clearly answers both what AND when with explicit triggers' anchor rather than leaving when implied (2).

"Use when two concurrent transactions can touch the same rows (balance debit, seat booking, stock decrement), or before changing a service's default isolation level" surfaces natural scenario terms a user would actually say; it exceeds the 'some relevant keywords' bar (2) with good coverage of common variations.

The MVCC isolation-testing niche with triggers like concurrent-row conflicts and isolation-level changes is clearly distinct and unlikely to trigger for unrelated skills; it clears the 'clear niche with distinct triggers' anchor instead of overlapping with similar skills (2).