import type {
CallToolRequest,
CallToolResultSchema,
} from "@modelcontextprotocol/sdk/types.js";
import type { z } from "zod";
export type CallToolRequestParams = CallToolRequest["params"];
export type CallToolResult = z.infer<typeof CallToolResultSchema>;
export interface CallToolTrace {
request: CallToolRequestParams;
result: CallToolResult;
}
export interface CallToolInterception<T extends boolean = boolean> {
shouldIntercept: (call: CallToolRequestParams) => T;
intercept: (call: CallToolRequestParams) => Promise<CallToolResult>;
}
const errorThrowingInterceptor: CallToolInterception<true> = {
shouldIntercept: () => true,
intercept: () => {
throw new Error("No interceptor found");
},
};
export function callToolInterceptor(
interceptors: CallToolInterception[],
defaultInterceptor: CallToolInterception<true> = errorThrowingInterceptor,
) {
const toolCallTraces: CallToolTrace[] = [];
return {
async call(request: CallToolRequestParams): Promise<CallToolResult> {
const interceptor =
interceptors.find((i) => i.shouldIntercept(request)) ??
defaultInterceptor;
const result = await interceptor.intercept(request);
toolCallTraces.push({ request, result });
return result;
},
get toolCallTraces(): readonly CallToolTrace[] {
return toolCallTraces;
},
};
}
