@type t() :: %Codex.Agent{
  handoff_description: String.t() | nil,
  handoffs: list(),
  hooks: term(),
  input_guardrails: list(),
  instructions: String.t() | nil,
  model: String.t() | nil,
  model_settings: map() | struct() | nil,
  name: String.t() | nil,
  output_guardrails: list(),
  prompt: map() | String.t() | nil,
  reset_tool_choice: boolean(),
  tool_input_guardrails: list(),
  tool_output_guardrails: list(),
  tool_use_behavior:
    :run_llm_again
    | :stop_on_first_tool
    | %{optional(:stop_at_tool_names) => [String.t()]}
    | function()
    | nil,
  tools: list()
}