This is optional and defaults to "assistant". When role=assistant, content is said out loud. When role=system, content is passed to the model in a system message. Example: system: default one assistant: user: assistant: user: assistant: user: assistant: tool called tool: your server response <— system prompt as hint —> model generates response which is spoken This is useful when you want to provide a hint to the model about what to say next.
This message is triggered when the tool call starts. This message is never triggered for async tools. If this message is not provided, one of the default filler messages "Hold on a sec", "One moment", "Just a sec", "Give me a moment" or "This’ll just take a sec" will be used.