Changelog

1. Handoff Tool and Dynamic Agent Routing: You can now hand off conversations when building multi-agent systems with Assistant.model.tools[type=handoff]. Supported destinations include:

• Assistant Destinations: Directly hand off to a specific assistant by assistantId or assistantName.
• Dynamic Destinations: Route handoffs dynamically via a webhook to your server, which can determine the destination assistant in real time. Custom parameters such as customer intent, sentiment, or area code can be passed to the webhook for advanced routing logic.
• Multiple Destinations: Support for both single handoff destination per tool with multiple tools (recommended for OpenAI) and multiple handoff destinations with one tool (recommended for Anthropic).

You can read more about how to configure the handoff tool in the API Reference

2. Context Engineering for Handoffs: When handing off a conversation, you can now control what context is passed to the next assistant:

• All Messages: Pass the entire conversation history. Refer to Context Engineering Plan All
• Last N Messages: Pass only the most recent N messages. Refer to Context Engineering Plan LastNMessages
• None: Pass no prior context. Refer to Context Engineering Plan None This gives you fine-grained control over privacy, relevance, and prompt size during agent transitions.

3. Message Metadata: Tool Messages, Assistant Messages, and Developer Messages objects now support an optional metadata field, allowing you to attach arbitrary metadata to messages for downstream processing or analytics.

4. Pagination Meta Enhancement: You can now reference itemsBeyondRetention boolean in paginated responses to indicate if additional items exist beyond the retention window.