MCP Elicitations Demo Server

import { Server } from "@modelcontextprotocol/sdk/server/index.js"; import { ListResourcesRequestSchema, ListResourceTemplatesRequestSchema, ReadResourceRequestSchema, SubscribeRequestSchema, UnsubscribeRequestSchema, } from "@modelcontextprotocol/sdk/types.js"; import { PAGE_SIZE, getResourceTemplates as getTemplates, readStaticResource, } from "./resource-static.js"; import { generateAllResources } from "../lib/resources.js"; import { requestTextSampling } from "../lib/sampling.js"; export const getAllResources = generateAllResources; export const getPageSize = () => PAGE_SIZE; export const getResourceTemplates = getTemplates; export const readResource = readStaticResource; // Setup function to handle all resource-related request handlers export const setupResources = (server: Server, subscriptions: Set<string>) => { const ALL_RESOURCES = getAllResources(); const PAGE_SIZE = getPageSize(); // Handle listing resources with pagination server.setRequestHandler(ListResourcesRequestSchema, async (request) => { const cursor = request.params?.cursor; let startIndex = 0; if (cursor) { const decodedCursor = parseInt(atob(cursor), 10); if (!isNaN(decodedCursor)) { startIndex = decodedCursor; } } const endIndex = Math.min(startIndex + PAGE_SIZE, ALL_RESOURCES.length); const resources = ALL_RESOURCES.slice(startIndex, endIndex); let nextCursor: string | undefined; if (endIndex < ALL_RESOURCES.length) { nextCursor = btoa(endIndex.toString()); } return { resources, nextCursor, }; }); // Handle listing resource templates server.setRequestHandler(ListResourceTemplatesRequestSchema, async () => { return { resourceTemplates: getResourceTemplates(), }; }); // Handle reading individual resources server.setRequestHandler(ReadResourceRequestSchema, async (request) => { const uri = request.params.uri; const resource = readResource(uri); if (resource) { return { contents: [resource], }; } throw new Error(`Unknown resource: ${uri}`); }); // Handle resource subscriptions server.setRequestHandler(SubscribeRequestSchema, async (request) => { const { uri } = request.params; subscriptions.add(uri); // Request sampling from client when someone subscribes await requestTextSampling( `A new subscription was started for resource: ${uri}`, "You are a helpful assistant that acknowledges resource subscriptions.", 100, server, undefined ); return {}; }); // Handle resource unsubscriptions server.setRequestHandler(UnsubscribeRequestSchema, async (request) => { subscriptions.delete(request.params.uri); return {}; }); }; // Helper function to handle resource completion export const handleResourceCompletion = (params: any) => { const { ref, argument } = params; const resourceId = ref.uri.split("/").pop(); if (!resourceId) return { completion: { values: [] } }; const completions = ["1", "2", "3", "4", "5"]; // Filter resource IDs that start with the input value const values = completions.filter((id: string) => id.startsWith(argument.value) ); return { completion: { values, hasMore: false, total: values.length } }; };