/**
 * @fileoverview Shared helpers for normalizing tool inputs into API search parameters.
 * @module mcp-server/tools/definitions/query-helpers
 */
/**
 * Normalize `string | string[]` to `string[]`.
 *
 * LLM callers intermittently serialize array arguments as JSON strings
 * (`'["RECRUITING","COMPLETED"]'` rather than `["RECRUITING","COMPLETED"]`). A
 * `[`-leading string that `JSON.parse`s to an all-string array is unwrapped to
 * that array. Every legitimate scalar this normalizes (status/phase enums, NCT
 * IDs, PascalCase field names) starts with a letter, so a `[`-leading string is
 * always either a stringified array or garbage — and garbage falls through to
 * the scalar-wrap, preserving the prior behavior.
 */
export declare function toArray(v: string | string[]): string[];
export declare function toArray(v: string | string[] | undefined): string[] | undefined;
/** Build AREA[] phase filter and combine with user's advancedFilter. */
export declare function buildAdvancedFilter(phaseFilter?: string[], advancedFilter?: string): string | undefined;
//# sourceMappingURL=query-helpers.d.ts.map