Semantic Alerts

Semantic alerts use AI to analyze content based on a natural language description you provide, rather than matching on exact keywords. Instead of monitoring for a specific word or phrase, you describe what you are looking for, and the system evaluates new content against your criteria.


How It Works

Content reaches a semantic alert through two paths:

  1. Direct site monitoring: When you create a semantic alert, you can select which sites and content types to monitor (Hacker News posts/comments, Lobsters posts/comments, Reddit posts/comments). All new content from those sources is automatically analyzed against your description.
  2. Keyword routing: You can add the semantic="alert name" flag to any of your keyword alerts. When that keyword matches, the content is forwarded to the named semantic alert for deeper analysis. This lets you use fast keyword matching as a first filter before AI evaluation.

Both paths can be used together on the same semantic alert.


Creating a Semantic Alert

Create and manage semantic alerts from the Semantic Alerts Dashboard. Each alert has the following fields:

Alert NameA unique name for the alert (1-32 characters). This name is also used when linking keyword alerts via the semantic= flag.
DescriptionA natural language description of what you are looking for (50-1,000 characters). Be as specific as possible. The AI evaluates every piece of content against this description to decide if it is a match.
Content SourcesSelect which sites and content types (posts, comments) to monitor directly.
SubredditsIf Reddit is selected, you can specify which subreddits to monitor. Enter subreddit names separated by spaces, without the /r/ prefix. If left blank and Reddit is selected, no Reddit content will be monitored directly (though content can still arrive via the semantic= flag on keyword alerts).

Writing a Good Description

The description is the most important part of a semantic alert. The AI uses it as its sole criteria for deciding whether content is a match. A vague description will produce noisy results; a specific one will produce precise matches.

Tips:


Options

The following options are available when creating or editing a semantic alert:

InstantBypass your account's email delay and send the alert immediately when a match is found.
Full TextInclude the full text of a matching post or comment in the alert, instead of a short excerpt.
GroupAssign the alert to a named group. Alerts in the same group are bundled into a separate email. Group names also let you filter alerts on the dashboard and in RSS/JSON feeds.

The semantic= Flag

You can route content from your keyword alerts into a semantic alert by adding the semantic= flag. When a keyword alert matches, the matched content is forwarded to the named semantic alert for AI analysis. The content is only delivered to you if the AI confirms it meets your semantic criteria.

Example:
Route matches to the "PM Tool Leads" semantic alert.

In this example, any post or comment containing "project management" is forwarded to the semantic alert named "PM Tool Leads". The AI then evaluates whether the content matches the description you set on that semantic alert. Only confirmed matches generate a notification.

If the alert name contains spaces, it must be enclosed in double quotes (e.g., semantic="pm tool leads"). For single-word names, quotes are not necessary (e.g., semantic=leads).


Limits

FreePowerUltra
Semantic Alerts002
Subreddits Per Alert005

Semantic alerts incur LLM token usage costs, which are billed separately in addition to your subscription tier cost. You can review your usage on the LLM Usage & Billing page.

View all account tiers.