/**
 * _meta — Transport-agnostic system parameter namespace
 *
 * Clients attach `_meta` to tool call arguments for system-level hints.
 * The runtime strips it before method invocation — methods never see it.
 *
 * Supported keys:
 *   format   — Output format: csv, json, yaml, markdown, html
 *   viewport — Container size hint: { width, height? }
 *   fields   — Field projection: { include?: [], exclude?: [] }
 *   locale   — Localization: { language?, timezone? }
 */
export interface MetaParams {
    format?: string;
    viewport?: {
        width: number;
        height?: number;
    };
    fields?: {
        include?: string[];
        exclude?: string[];
    };
    locale?: {
        language?: string;
        timezone?: string;
    };
}
export interface MetaFormattedResult {
    _metaFormatted: true;
    text: string;
    mimeType: string;
}
/**
 * Extract `_meta` from tool call arguments.
 * Returns clean args (without _meta) and the extracted meta params.
 */
export declare function stripMeta(args: Record<string, unknown>): {
    cleanArgs: Record<string, unknown>;
    meta?: MetaParams;
};
/**
 * Apply _meta transformations to a tool result.
 * Pipeline: field selection → format transformation.
 *
 * @param result - Raw method return value
 * @param meta - Extracted _meta params
 * @param exportFormats - Allowed formats from @export tag (undefined = defaults)
 * @returns Transformed result, or MetaFormattedResult wrapper for text formats
 */
export declare function applyMeta(result: unknown, meta: MetaParams, exportFormats?: string[]): unknown;
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