`String(x)`, `Number(x)`, or `Boolean(x)` applied to a parameter already typed as that primitive. The conversion repeats what the type system already guarantees.
Each example shows the exact code shape the rule is looking for, then the smallest version that keeps the intent without hiding risk or adding noise.
export function formatPrice(amount: number, currency: string) {
const value = Number(amount)
return `${String(currency)} ${value.toFixed(2)}`
}Deterministic AST match on TypeScript: flags `String()`, `Number()`, or `Boolean()` called on a parameter annotated `string`, `number`, or `boolean` respectively, within that function's own body.
export function formatPrice(amount: number, currency: string) {
return `${currency} ${amount.toFixed(2)}`
}Trust the typed boundary and drop the conversion, or validate unknown input once, where it enters the system.
Agents coerce inputs defensively in case a caller passes the wrong type, even when the signature rules that out.
ai-slop/redundant-type-coercion
ai-slop
Deterministic AST match on TypeScript: flags `String()`, `Number()`, or `Boolean()` called on a parameter annotated `string`, `number`, or `boolean` respectively, within that function's own body.
Coercion of `unknown` or untyped values, conversions between different primitives (`Number(s)` on a string), plain JavaScript files, and calls inside nested functions are not flagged.
Part of aislop's defensive-pattern detectors for TypeScript, scored in the maintainability tier.