import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { CallToolResult } from "@modelcontextprotocol/sdk/types.js";
import {
beginSimulatedResourceUpdates,
stopSimulatedResourceUpdates,
} from "../resources/subscriptions.js";
// Tool configuration
const name = "toggle-subscriber-updates";
const config = {
title: "Toggle Subscriber Updates",
description: "Toggles simulated resource subscription updates on or off.",
inputSchema: {},
};
// Track enabled clients by session id
const clients: Set<string | undefined> = new Set<string | undefined>();
/**
* Registers the `toggle-subscriber-updates` tool.
*
* The registered tool enables or disables the sending of periodic, simulated resource
* update messages the connected client for any subscriptions they have made.
*
* When invoked, it either starts or stops simulated resource updates based on the session's
* current state. If simulated updates for the specified session is active, it will be stopped;
* if it is inactive, simulated updates will be started.
*
* The response provides feedback indicating whether simulated updates were started or stopped,
* including the session ID.
*
* @param {McpServer} server - The McpServer instance where the tool will be registered.
*/
export const registerToggleSubscriberUpdatesTool = (server: McpServer) => {
server.registerTool(
name,
config,
async (_args, extra): Promise<CallToolResult> => {
const sessionId = extra?.sessionId;
let response: string;
if (clients.has(sessionId)) {
stopSimulatedResourceUpdates(sessionId);
clients.delete(sessionId);
response = `Stopped simulated resource updates for session ${sessionId}`;
} else {
beginSimulatedResourceUpdates(server, sessionId);
clients.add(sessionId);
response = `Started simulated resource updated notifications for session ${sessionId} at a 5 second pace. Client will receive updates for any resources the it is subscribed to.`;
}
return {
content: [{ type: "text", text: `${response}` }],
};
}
);
};
