/**
 * Tool result size guard for agentic loops.
 *
 * Prevents oversized tool results (e.g. base64 image data) from
 * bloating the LLM message history and exceeding token limits.
 */
/**
 * Sanitize a tool result for inclusion in the LLM message history.
 *
 * - If the serialized result is within limits, returns it unchanged.
 * - If it contains base64 image data, strips the binary and adds guidance.
 * - Otherwise truncates with a preview.
 */
export declare function sanitizeToolResult(result: any): string;