import { Transport } from "@modelcontextprotocol/sdk/shared/transport.js";
import { McpToolsLogger, UrlBasedConfig } from "./langchain-mcp-tools.js";
/**
 * Creates an HTTP transport with automatic fallback from Streamable HTTP to SSE.
 * Follows the MCP specification recommendation to test with direct POST InitializeRequest first,
 * then fall back to SSE if a 4xx error is encountered.
 *
 * See: https://modelcontextprotocol.io/specification/2025-03-26/basic/transports#backwards-compatibility
 *
 * @param url - The URL to connect to
 * @param config - URL-based server configuration
 * @param logger - Logger instance for recording connection attempts
 * @param serverName - Server name for logging context
 * @returns A promise that resolves to a configured Transport
 *
 * @internal This function is meant to be used internally by convertSingleMcpToLangchainTools
 */
export declare function createHttpTransportWithFallback(url: URL, config: UrlBasedConfig, logger: McpToolsLogger, serverName: string): Promise<Transport>;