/**
 * Apply a JMESPath filter to JSON data
 *
 * @param data - The data to filter (any JSON-serializable value)
 * @param filter - JMESPath expression to apply
 * @returns Filtered data or original data if filter is empty/invalid
 *
 * @example
 * // Get single field
 * applyJqFilter(data, "name")
 *
 * // Get nested field
 * applyJqFilter(data, "body.storage.value")
 *
 * // Get multiple fields as object
 * applyJqFilter(data, "{id: id, title: title}")
 *
 * // Array operations
 * applyJqFilter(data, "results[*].title")
 */
export declare function applyJqFilter(data: unknown, filter?: string): unknown;
/**
 * Convert data to JSON string for MCP response
 *
 * @param data - The data to stringify
 * @param pretty - Whether to pretty-print the JSON (default: true)
 * @returns JSON string
 */
export declare function toJsonString(data: unknown, pretty?: boolean): string;
/**
 * Convert data to output string for MCP response
 *
 * By default, converts to TOON format (Token-Oriented Object Notation)
 * for improved LLM token efficiency (30-60% fewer tokens).
 * Falls back to JSON if TOON conversion fails or if useToon is false.
 *
 * @param data - The data to convert
 * @param useToon - Whether to use TOON format (default: true)
 * @param pretty - Whether to pretty-print JSON (default: true)
 * @returns TOON formatted string (default), or JSON string
 */
export declare function toOutputString(data: unknown, useToon?: boolean, pretty?: boolean): Promise<string>;