# /sub-agents A sub-agent is one cheap model doing one clear part of a task for the chat model. It exists to save credit: the expensive model plans and checks, the cheap one does the mechanical work. You do not need [Ultracode](https://zerolog.ch/docs/ultracode) for it. Ask for it in plain words ``` use sub-agents to save money: read the 3 files in /work/probe and summarise them ``` When ## When the model hands work over When you want to save credit, or when a part is mechanical: reading several files and summarising them, reshaping data, trying variants. Not for small things it can finish in one step itself. Setup ## What a sub-agent gets - **Model**: Cheap by default Your own key: its helper model A dearer model asks you first - **Tools**: None, or run_command, read_file, write_file in the chat container Chat approvals apply - **Answer**: 1500 characters by default 6000 at most The chat model checks it Limits ## Hard limits At most 4 sub-agents at the same time in a chat and 8 per turn, each with its own spend cap. A sub-agent cannot start more sub-agents or an Ultracode workflow. **Stop** stops them together with the rest of the turn. Cost ## What it costs With your own key, nothing for the platform. On the cheap platform tier the cost goes into the normal billing, bounded by the delegation spend cap. Each sub-agent shows as a compact card in the chat with its log.