MCP Elicitations Demo Server

Instructions

Implementation Reference

• src/tools/tool-long-running-operation.ts:17-48 (handler)

  The handler function that executes the long-running operation logic, parsing inputs, simulating steps with delays, sending progress notifications if available, and returning a completion message.

  handler: async (args: any, request: any, server: Server) => {
    const validatedArgs = LongRunningOperationSchema.parse(args);
    const { duration, steps } = validatedArgs;
    const stepDuration = duration / steps;
    const progressToken = request.params._meta?.progressToken;
  
    for (let i = 1; i < steps + 1; i++) {
      await new Promise((resolve) =>
        setTimeout(resolve, stepDuration * 1000)
      );
  
      if (progressToken !== undefined) {
        await server.notification({
          method: "notifications/progress",
          params: {
            progress: i,
            total: steps,
            progressToken,
          },
        });
      }
    }
  
    return {
      content: [
        {
          type: "text" as const,
          text: `Long running operation completed. Duration: ${duration} seconds, Steps: ${steps}.`,
        },
      ],
    };
  },

• src/tools/tool-long-running-operation.ts:5-11 (schema)

  Zod schema for validating tool inputs: duration (default 10 seconds) and steps (default 5). Used in handler and converted to JSON schema for inputSchema.

  const LongRunningOperationSchema = z.object({
    duration: z
      .number()
      .default(10)
      .describe("Duration of the operation in seconds"),
    steps: z.number().default(5).describe("Number of steps in the operation"),
  });

• src/tools/index.ts:22-37 (registration)

  Registration of the longRunningOperationTool in the allTools array, which is used by getTools() to list tools and getToolHandler() to find the handler for execution.

  const allTools = [
    echoTool,
    addTool,
    longRunningOperationTool,
    printEnvTool,
    sampleLlmTool,
    sampleWithPreferencesTool,
    sampleMultimodalTool,
    sampleConversationTool,
    sampleAdvancedTool,
    getTinyImageTool,
    annotatedMessageTool,
    getResourceReferenceTool,
    elicitationTool,
    getResourceLinksTool,
  ];

• src/tools/index.ts:53-70 (registration)

  Setup function that registers the general request handlers for listing tools (ListToolsRequestSchema) and calling tools (CallToolRequestSchema) on the MCP server, enabling execution of longRunningOperationTool.

  export const setupTools = (server: Server) => {
    // Handle listing all available tools
    server.setRequestHandler(ListToolsRequestSchema, async () => {
      return { tools: getTools() };
    });
  
    // Handle tool execution
    server.setRequestHandler(CallToolRequestSchema, async (request) => {
      const { name, arguments: args } = request.params;
      const handler = getToolHandler(name);
  
      if (handler) {
        return await handler(args, request, server);
      }
  
      throw new Error(`Unknown tool: ${name}`);
    });
  };