Optuna MCP Server

Instructions

Implementation Reference

• optuna_mcp/server.py:220-237 (handler)

  The main handler function for the 'set_trial_user_attr' tool. It retrieves the trial ID from the study's storage and calls storage.set_trial_user_attr to set the user attribute for the specified trial.

  @mcp.tool(structured_output=True)
  def set_trial_user_attr(trial_number: int, key: str, value: typing.Any) -> str:
      """Set user attributes for a trial"""
      if mcp.study is None:
          raise McpError(
              ErrorData(
                  code=INTERNAL_ERROR,
                  message="No study has been created. Please create a study first.",
              )
          )
  
      storage = mcp.study._storage
      trial_id = storage.get_trial_id_from_study_id_trial_number(
          mcp.study._study_id, trial_number
      )
      storage.set_trial_user_attr(trial_id, key, value)
      return f"User attribute {key} set to {json.dumps(value)} for trial {trial_number}"