monitor_feed_updates

Instructions

Implementation Reference

• src/index.ts:185-236 (handler)

  The execute handler function that fetches the RSS feed, computes the 'since' timestamp, filters for new items based on publish/update dates, updates the cache, and returns a structured response with new items and metadata.

  execute: async (args, context) => {
    logger.info(`Monitoring updates for: ${args.url} since ${args.since}`);
  
    // Get current feed state
    const currentFeed = await rssReader.fetchFeed(args.url);
  
    let sinceTimestamp: number;
  
    if (args.since === "last") {
      // Get last fetch time from cache
      const cached = feedCache.get(args.url);
      if (cached) {
        sinceTimestamp = cached.fetchedAt;
      } else {
        // If no cache, return all items as new
        sinceTimestamp = 0;
      }
    } else {
      sinceTimestamp = args.since;
    }
  
    // Filter items newer than timestamp
    const newItems = currentFeed.items.filter((item) => {
      const itemTime = item.published || item.updated || 0;
      return itemTime > sinceTimestamp;
    });
  
    // Update cache
    feedCache.set(args.url, currentFeed);
  
    logger.info(
      `Found ${newItems.length} new items since ${new Date(
        sinceTimestamp
      ).toISOString()}`
    );
  
    return JSON.stringify(
      {
        feedUrl: args.url,
        feedTitle: currentFeed.info.title,
        since: sinceTimestamp,
        sinceISO: new Date(sinceTimestamp).toISOString(),
        checkedAt: currentFeed.fetchedAt,
        checkedAtISO: new Date(currentFeed.fetchedAt).toISOString(),
        newItemsCount: newItems.length,
        totalItemsCount: currentFeed.items.length,
        newItems,
      },
      null,
      2
    );
  },

• src/index.ts:170-178 (schema)

  Zod schema defining input parameters: url (string) and since (number timestamp or 'last').

  const MonitorFeedUpdatesSchema = z.object({
    url: z.string().describe("The RSS feed URL to monitor"),
    since: z
      .union([
        z.number().describe("Timestamp in milliseconds to check updates since"),
        z.literal("last").describe("Check updates since last fetch"),
      ])
      .describe("Time reference for checking updates"),
  });

• src/index.ts:180-237 (registration)

  Registers the 'monitor_feed_updates' tool with the FastMCP server, specifying name, description, parameter schema, and execute handler.

  server.addTool({
    name: "monitor_feed_updates",
    description:
      "Check for new items in a feed since a specific time or last check",
    parameters: MonitorFeedUpdatesSchema,
    execute: async (args, context) => {
      logger.info(`Monitoring updates for: ${args.url} since ${args.since}`);
  
      // Get current feed state
      const currentFeed = await rssReader.fetchFeed(args.url);
  
      let sinceTimestamp: number;
  
      if (args.since === "last") {
        // Get last fetch time from cache
        const cached = feedCache.get(args.url);
        if (cached) {
          sinceTimestamp = cached.fetchedAt;
        } else {
          // If no cache, return all items as new
          sinceTimestamp = 0;
        }
      } else {
        sinceTimestamp = args.since;
      }
  
      // Filter items newer than timestamp
      const newItems = currentFeed.items.filter((item) => {
        const itemTime = item.published || item.updated || 0;
        return itemTime > sinceTimestamp;
      });
  
      // Update cache
      feedCache.set(args.url, currentFeed);
  
      logger.info(
        `Found ${newItems.length} new items since ${new Date(
          sinceTimestamp
        ).toISOString()}`
      );
  
      return JSON.stringify(
        {
          feedUrl: args.url,
          feedTitle: currentFeed.info.title,
          since: sinceTimestamp,
          sinceISO: new Date(sinceTimestamp).toISOString(),
          checkedAt: currentFeed.fetchedAt,
          checkedAtISO: new Date(currentFeed.fetchedAt).toISOString(),
          newItemsCount: newItems.length,
          totalItemsCount: currentFeed.items.length,
          newItems,
        },
        null,
        2
      );
    },
  });

• src/types.ts:90-93 (schema)

  TypeScript interface defining the tool's input parameters, matching the Zod schema.

  export interface MonitorFeedUpdatesParams {
    url: string;
    since: number | 'last';
  }