monitor_feed_updates

Track new items in an RSS feed by specifying a URL and checking updates since a specific time or the last fetch, ensuring timely content monitoring.

Instructions

Check for new items in a feed since a specific time or last check

Input Schema

TableJSON Schema

Name	Required	Description	Default
`since`	Yes	Time reference for checking updates
`url`	Yes	The RSS feed URL to monitor

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';
}
```

@missionsquad/mcp-rss