/**
 * @name payments/schema-validation
 * @description Pre-payment schema validation for x402 paid tool calls.
 *
 * Validates tool arguments against the local registration store's JSON Schema
 * BEFORE the x402 challenge is fetched and paid. This prevents wasted USDC
 * on calls with invalid schemas (e.g. wrong parameter names, missing required
 * fields).
 *
 * If the tool name is not found in the local registration store (hosted-only
 * tools), validation is skipped — we cannot validate what we don't have the
 * schema for. This is intentionally non-breaking: existing behavior is
 * preserved for unknown tools.
 *
 * @module payments/schema-validation
 */
import type { Server } from '@modelcontextprotocol/sdk/server/index.js';
/**
 * Store the server reference for pre-payment schema validation.
 * Called once during registerX402PaidCallTool().
 * @param server — The MCP server instance with registered tools.
 */
export declare function setValidationServer(server: Server): void;
/**
 * Validation result for a tool's input arguments.
 */
export interface SchemaValidationResult {
    /** True if arguments match the tool's schema. */
    valid: boolean;
    /** Human-readable validation errors (empty if valid). */
    errors: string[];
    /** True if validation was skipped (tool not found locally). */
    skipped: boolean;
    /** Tool name that was validated. */
    toolName: string;
}
/**
 * Validate tool arguments against the local registration store's JSON Schema.
 *
 * Uses simple runtime type checking against the JSON Schema properties —
 * checks required fields, enum values, and basic types. This is intentionally
 * lightweight (no ajv dependency) to keep the bridge fast and dependency-free.
 *
 * If the tool is not registered locally, returns `skipped: true` and
 * `valid: true` — the caller should proceed with the x402 flow as normal.
 *
 * @param toolName — Name of the tool to validate against.
 * @param args — Arguments to validate.
 * @returns SchemaValidationResult with validity and error details.
 */
export declare function validateToolArguments(toolName: string, args: unknown): SchemaValidationResult;
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