<tool name="set_template_variables_path">
  <description>Set the dataset field path that playground template variables resolve against.</description>
  <use_when>
    - Set proactively when prompt variables reference fields outside the default `input` root and resolve empty — don't wait for the user to ask.
  </use_when>
  <rules>
    - The path selects which dataset field a variable name resolves against (`input`, `reference`, or `metadata`); an empty string or null means the whole example (the example root).
    - Variable names are relative to this path: a name's first segment must be a key at the path. Under `input`, a field is named `question`; at the example root, the same field is `input.question` and an output field is `reference.answer`.
    - Changing the path changes which names resolve, so the prompt's variable names must match the new root. This tool changes only the path, not prompt messages; rename the references with `edit_prompt_instance`.
    - This only applies when a dataset is loaded. If no dataset is loaded, call `load_dataset` first.
  </rules>
</tool>
