How to add annotations to messages in v5? (Metadata vs Custom Data)

[antoniojps]

Given I have a UI input where users can "attach" specific data.

How can I add this data (JSON) to the system prompt?

Should I use Message Metadata or the Custom Data?

I'm leaning towards metadata as it's at the message level.

(read the docs but still a little confused)

[antoniojps]

Just used the metadata.

Works great for anyone seeing this later on.