Callstack Reviewer supports specifying model, token and endpoint for all LLM calls. Model can be specified either at the top level - which overrides models in all modules - or on per module basis. Example configuration: 
pr_review:
  # specify model globally for all modules
  model:
    model: "gpt-4o"
    token: <model token>
    base_url: <endpoint base url>

  # specify model for specific module
  modules:
    bug_hunter:
      model:
        model: "claude-3-5-sonnet-20241022"
        token: <model token>
        base_url: <endpoint base url>
We highly recommend keeping the default model configuration for the best performance.