Writing effective monitoring criteria
How to phrase plain-English criteria so monitors catch what you want and stay quiet about what you don't.
The criterion is what separates a useful monitor from a noisy one. A vague criterion ("alert me on any change") generates too many false positives on a busy page. An over-specific criterion ("alert me only when the price is exactly $X.XX") misses the broader signal. This guide covers what makes a criterion work, the patterns that consistently fail, and how to debug a monitor that's too noisy or too quiet.
Be specific about the property, not the value
Strong criterion: "alert me when the price drops below $X." Weak criterion: "alert me when this page changes." The strong version targets a specific property (price) and a specific condition (below threshold). The weak version catches everything — banner updates, photo swaps, sidebar changes — and produces alert fatigue.
Use thresholds for numeric criteria
Numeric data (prices, stock levels, ratings, response times) benefits from threshold criteria over absolute equality. "Alert me when the response time exceeds 2 seconds for three consecutive checks" is more useful than "alert me when response time is exactly 2.0s" — the second never fires.
For content monitoring, name the topic
Strong: "alert me when a new article tagged with [topic] is published." Weak: "alert me when there's a new blog post." The strong version filters out off-topic posts; the weak version alerts on every publishing day. Specificity reduces noise.
Combine criteria when one isn't enough
Sometimes a single criterion catches too much OR too little. "Alert me when this product is in stock AND under $X" is two criteria combined — both must be true to fire. Most tools support this; the syntax varies.
Debugging a noisy monitor
If a monitor is firing too often: review the last 5 alerts. Are they on changes you actually wanted to catch? If not, the criterion is too broad. Tighten it. Common case: the page has rotating banners or timestamps that change every visit — the criterion needs to ignore those zones.
Debugging a quiet monitor
If a monitor never fires when you expected it to: induce the change manually (refresh the page in a different browser to see what actually shows up). Verify the property you're monitoring is actually rendered on the page. Some sites server-side-render in a different format than they client-side-render — what the monitor sees and what you see in your browser may differ.
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