# tinker_cookbook.rl.ActionExtra

## _class_ [**tinker_cookbook.rl.ActionExtra**](https://github.com/thinking-machines-lab/tinker-cookbook/blob/main/tinker_cookbook/rl/types.py#L182)( _TypedDict_)

Extra metadata passed alongside an action to `Env.step`.

All fields are optional so that callers and env implementations can ignore keys they don't care about. Values must be picklable (the rollout executor may serialise them across process boundaries).

**Fields:**

- [**stop_reason**](https://github.com/thinking-machines-lab/tinker-cookbook/blob/main/tinker_cookbook/rl/types.py#L190) ( _tinker. [StopReason](https://tinker-docs.thinkingmachines.ai/cookbook/api-reference/rl/stopreason/)_) – Why sampling stopped — `