<tool name="clone_prompt_instance">
  <description>Duplicate an existing playground prompt instance into a fresh comparison instance so the user can compare a proposed variant against the original side by side.</description>
  <when_to_use>
    - The user wants to try a prompt change as a comparison rather than overwriting the current instance.
    - You are about to propose edits with `edit_prompt_instance` and the user has indicated they want to keep the original visible alongside the variant.
  </when_to_use>
  <guidelines>
    - Use the alphabetic instance labels (A, B, C, D) when discussing instances with the user, but pass the numeric `instanceId` when calling tools.
    - If there is exactly one playground instance, `instanceId` may be omitted. With multiple comparison instances, pass the specific `instanceId` you want to clone.
    - The playground supports at most 4 comparison instances; this tool is rejected when 4 instances already exist. If the limit is reached, ask the user which instance to remove (or whether to overwrite an existing instance instead) before retrying.
    - The clone receives fresh message IDs. After cloning, call `read_prompt_instance` on the new instance to obtain its message IDs and revision before calling `edit_prompt_instance`.
  </guidelines>
</tool>
