MCP Elicitations Demo Server

import { z } from "zod"; import { zodToJsonSchema } from "zod-to-json-schema"; import { Server } from "@modelcontextprotocol/sdk/server/index.js"; import { requestSampling, Message } from "../lib/sampling.js"; const ConversationMessageSchema = z.object({ role: z.enum(["user", "assistant"]).describe("Message role in conversation"), text: z.string().describe("Message text content"), }); const ConversationSampleSchema = z.object({ conversation: z .array(ConversationMessageSchema) .min(1) .describe("Conversation history (alternating user/assistant messages)"), systemPrompt: z .string() .default("You are a helpful assistant engaged in a conversation.") .describe("System prompt to guide the conversation style"), maxTokens: z .number() .default(150) .describe("Maximum number of tokens to generate"), modelHint: z .string() .optional() .describe( "Preferred model hint for conversation (e.g., 'claude-3-sonnet')" ), }); export const sampleConversationTool = { name: "sampleConversation", description: "Continue a conversation by sampling the next assistant response", inputSchema: zodToJsonSchema(ConversationSampleSchema), handler: async (args: any, request: any, server: Server) => { const validatedArgs = ConversationSampleSchema.parse(args); const { conversation, systemPrompt, maxTokens, modelHint } = validatedArgs; // Convert conversation to messages format const messages: Message[] = conversation.map((msg: any) => ({ role: msg.role, content: { type: "text", text: msg.text, }, })); // Build model preferences if hint provided const modelPreferences = modelHint ? { hints: [{ name: modelHint }], intelligencePriority: 0.8, // Prefer intelligent models for conversation speedPriority: 0.6, // Moderate speed priority costPriority: 0.3, // Cost is less important for conversation quality } : undefined; const result = await requestSampling( { messages, systemPrompt, maxTokens, modelPreferences, }, server ); // Format the conversation display const conversationDisplay = conversation .map( (msg: any, index: number) => `${msg.role.toUpperCase()}: ${msg.text}` ) .join("\n"); return { content: [ { type: "text" as const, text: `Conversation Continuation: Previous Messages: ${conversationDisplay} ASSISTANT: ${result.content.text} --- Model: ${result.model || "unknown"} Stop Reason: ${result.stopReason || "unknown"}`, }, ], }; }, };