Querying Signals

What Are Signals?

Signals are automated observations that PostHog generates by monitoring a customer's product data across multiple sources — error tracking, web analytics, experiments, session replay, and more. Each signal is a short natural-language description of something noteworthy (e.g. "Error rate spiked 3× on /checkout").

Signals are grouped into Signal Reports. When a report accumulates enough weight it gets summarized and assessed for actionability. A signal report represents a cluster of related observations that together describe a meaningful issue or trend.

Signals and their embeddings are stored in the document_embeddings ClickHouse table, queryable via HogQL through the posthog:execute-sql MCP tool. They may provide a useful way to semantically query for recent things that happened in the user's product.

When to use this skill vs. inbox-exploration

The two skills cover different layers of the same product:

• inbox-exploration — curated report layer via dedicated MCP tools (inbox-reports-list, inbox-reports-retrieve, inbox-source-configs-list, inbox-source-configs-retrieve). Use for "what's in my inbox?", "what's actionable?", filtering reports by status / source / suggested reviewer, looking up a specific report by ID or URL.
• This skill (signals) — raw signal layer via HogQL on document_embeddings. Use when the curated report layer is not enough: semantic search over signal text, fetching every signal that contributed to a specific report, listing what kinds of signals exist, or any ad-hoc analytics that the report tools don't expose.

The typical pattern is to start with inbox-exploration, get a report_id or a sense of the area the user cares about, then drop into this skill when the user wants to see the raw observations.