defineHarnessInstructions
Purpose and behavior
Section titled “Purpose and behavior”Define system instructions from text or from a resolver called at the start of each turn with the sandbox, signal, model and MCP context. The resolved text is not stored in the conversation.
Complete example and detailed rules.
Parameters and properties
Section titled “Parameters and properties”sourceRequiredHarnessInstructionSourceNonempty instruction text, or a function that receives the turn context and returns the text when the turn starts.