Find messages in an AgentMail inbox and return their metadata (id, thread, sender, recipients, subject, date, preview, labels) — not full bodies. With query, a full-text search of sender, recipients, subject and body, best match first. Without it, the newest messages, optionally filtered by labels and by from/to/subject substrings. Then read one with get_agentmail_message, or file it with update_agentmail_labels. Trashed and spam messages are skipped unless asked for.