Hi @TimMunro , this is a good question, and the short answer is: for standard HubSpot event types, you can’t retrieve a formal property schema the same way you can for custom events
The “event definitions” endpoint only applies to custom behavioral events that you’ve explicitly defined. For standard system events like e_v2_contact_clicked_sequence_email, HubSpot does not expose a public definition or contract that lists all possible properties and their types. Those events are considered internal, and their payload shape is effectively undocumented beyond what you see at runtime.
In practice, there are two workable approaches. The first is empirical: collect a representative sample of events from the events endpoint and inspect the properties object across multiple records to infer the available keys and value types.
This is what most teams end up doing for email, sequence, and page interaction events. The second is to rely on the higher-level APIs that do document their data model, for example the Email Events API, which is purpose-built for email interactions and has clearer semantics around fields like click URLs, campaign IDs, and recipient metadata (https://developers.hubspot.com/docs/api/marketing/email-events).
HubSpot hints at this limitation in the Events API docs by only promising property discovery for custom events, not standard ones (https://developers.hubspot.com/docs/api/events/overview).
There isn’t a hidden endpoint you’re missing. So if you need a stable, well-documented schema, the recommendation is usually to use the domain-specific APIs (email events, analytics, etc.). If you’re aggregating events generically, be prepared to treat properties as semi-structured data and version your own interpretation over time. Hope that saves you some digging.
