Review message limits
A message holds up to 100 parts, and up to 40 of them may be media imported from a public URL. Text and link parts have their own caps.Review chat limits
A chat holds one person and up to six agents, so a send names at most six other contacts. Page sizes for chat and message lists run from 1 to 100.Review attachment limits
Upload an attachment first and send its ID, or import from a public HTTPS URL. The two paths have different size caps.Review event limits
Webhook and WebSocket delivery have their own windows, described in delivery and retries and the frames reference.When it fails
A429 carries code 2008 and retry_after in seconds; wait that long, then retry with the same idempotency key. A 400, 413, 415, or 422 names the boundary you crossed: too many parts, an attachment over its cap, an unsupported type, or a body that failed validation. Branch on the numeric code from error codes, not on the HTTP status.