xmcp/dist/runtime/utils/transformers/tool.d.ts

The TypeScript MCP framework

import { CallToolResult, InputRequiredResult, ServerContext } from "@modelcontextprotocol/server";
import { ZodRawShape } from "zod/v3";
import type { ToolExtraArguments } from "@/types/tool";
/**
 * Type for the original tool handler that users write
 */
export type UserToolResponse = CallToolResult | InputRequiredResult | string | number | Record<string, unknown>;
export type UserToolHandler = (args: ZodRawShape, extra: ToolExtraArguments) => UserToolResponse | Promise<UserToolResponse>;
/**
 * Type for the transformed handler that the MCP server expects
 */
export type McpToolHandler = (args: ZodRawShape, ctx: ServerContext) => CallToolResult | InputRequiredResult | Promise<CallToolResult | InputRequiredResult>;
export declare function resolveToolClientInfo(ctx: ServerContext): ToolExtraArguments["clientInfo"];
/**
 * Transforms a user's tool handler into an MCP-compatible handler.
 *
 * This function:
 * 1. Passes through both args and extra parameters to the user's handler
 * 2. Transforms string/number responses into the required CallToolResult format
 * 3. Allows returning `content`, `structuredContent`, or both
 * 4. Allows returning only `_meta` (without `content`) when it contains widget metadata
 * 5. Auto-wraps HTML strings with widget metadata if provided
 * 6. Validates that the response is a proper CallToolResult and throws a descriptive error if not
 *
 * @param handler - The user's tool handler function
 * @param meta - Optional metadata to attach to responses (for MCP app widgets)
 * @returns A transformed handler compatible with McpServer.registerTool
 * @throws Error if the handler returns an invalid response type
 */
export declare function transformToolHandler(handler: UserToolHandler, meta?: Record<string, any>, outputSchema?: ZodRawShape, toolName?: string): McpToolHandler;