ChatMessage

A single message in a chat conversation.

roleRolerequired

Message role: 'user', 'assistant', 'system', or 'tool'

content object

Message content. Usually a string, but may be a multimodal content list (e.g. text + image_url) or null for assistant turns that only request tool calls.

anyOf

• Option 1
• null

tool_call_id object

For tool messages, the ID of the tool call

anyOf

• string
• null

string

name object

For tool messages, the tool name

anyOf

• string
• null

string

tool_calls object

For assistant messages replayed from prior turns, the OpenAI-format tool calls the model previously requested. Replaying these verbatim keeps the conversation prefix byte-for-byte identical so the model server's prompt cache hits on follow-up turns.

anyOf

• object[]
• null

Array [

object

]

ChatMessage

{
  "role": "string",
  "tool_call_id": "string",
  "name": "string",
  "tool_calls": [
    {}
  ]
}