Custom Parameters

Picking A Default Parameters Set

By default, when you specify a custom endpoint in librechat.yaml config file, it will use the default parameters of the OpenAI API. However, you can override these defaults by specifying the customParams.defaultParamsEndpoint field within the definition of your custom endpoint. For example, to use Google parameters for your custom endpoint:

endpoints:
  custom:
    - name: 'Google Gemini'
      apiKey: ...
      baseURL: ...
      customParams:
        defaultParamsEndpoint: 'google'

Your “Google Gemini” endpoint will now display parameters for Google API when you create a new agent or preset.

Overriding Parameter Definitions

On top of that, you can also fine tune the parameters provided for your custom endpoint. For example, the temperature parameter for google endpoint is a slide with range from 0.0 to 1.0, and default of 1.0, you can update the librechat.yaml file to override these values:

endpoints:
  custom:
    - name: 'Google Gemini'
      apiKey: ...
      baseURL: ...
      customParams:
        defaultParamsEndpoint: 'google'
        paramDefinitions:
          - key: temperature
            range:
              min: 0
              max: 0.7
              step: 0.1
            default: 0.5

As a result, the Temperature slider will be limited to the range of 0.0 and 0.7 with step of 0.1, and a default of 0.5. The rest of the parameters will be set to their default values.

Anthropic

When using defaultParamsEndpoint: 'anthropic', the system provides special handling that goes beyond just displaying and using Anthropic parameter sets:

This is mainly necessary to properly format the thinking parameter, which is not OpenAI-compatible:

{
  "thinking": {
    "type": "enabled",
    "budget_tokens": 10000
  }
}

Additionally, the system automatically adds model-specific Anthropic beta headers such as:

• anthropic-beta: prompt-caching-2024-07-31 for prompt caching support
• anthropic-beta: context-1m-2025-08-07 for extended context models
• Model-specific feature flags based on the Claude model being used

This ensures full compatibility when routing through proxy services or directly to Anthropic-compatible endpoints.