Authentication Settings define the requirements to successfully make an API Call, for example, OAuth Settings.
Example:

{
      "keys": {
        "client_secret": null, 
        "client_id": null
      }, 
      "meta": {
        "domain": "httpbin.org", 
        "description": null, 
        "created": "2015-09-14T23:19:52.888168Z", 
        "documentation": {
          "keys": null, 
          "docs": null, 
          "apps": null, 
          "provider": null
        }, 
        "last_update": "2015-09-14T23:19:52.888175Z", 
        "owner": "agxkZXZ-dmlhdGVzdHNyEQsSBFVzZXIYgICAgICAgAoM", 
        "tags": [], 
        "name": "Minimal Auth Settings name"
      }, 
      "id": "agxkZXZ-dmlhdGVzdHNyGgsSDVNlcnZpY2VDb25maWcYgICAgKDdjQgM", 
      "settings": {
        "auth_type": "NONE", 
        "custom_variables": {}
      }
    }

Name	Description	required?
meta	See section below	Yes
settings	See section below	Yes
keys	See section below	No

Section: meta

Name	Description	required?
name	Name for your reference	Yes
tags	List of tags for your reference	No
description	Description for your reference	No
owner	ID of owner	No - read-only
domain	The hostname for URLs that use this authentication	No
documentation	See below	No

Section: meta.documentation

Name	Description	required?
keys	Link to developer keys page for site	No
docs	Link to developer docs for site	No
apps	Link to developer app creation page for site	No
provider	Link to homepage for site	No

Section: settings

Name	Description	Required
auth_type	Kind of authentication, one of: "MANUAL", "BASIC", "OAUTH1", "OAUTH2", "NONE", "OAUTH2_JWS", "OAUTH2_JWT", "AMAZON"	Yes
custom_variables	Dictionary of custom variables for use in API calls	No
...	Other keys may be added depending on the Authentication Type.	No

{
  "access": {
    "keys": false, 
    "org_keys": false, 
    "org_settings": false, 
    "settings": false
  }, 
  "keys": {
    "client_secret": null, 
    "client_id": null
  }, 
  "meta": {
    "domain": "httpbin.org", 
    "description": null, 
    "documentation": {
      "keys": null, 
      "docs": null, 
      "apps": null, 
      "provider": null
    }, 
    "owner": "agxkZXZ-dmlhdGVzdHNyEQsSBFVzZXIYgICAgICAgAoM", 
    "tags": [], 
    "name": "Auth Settings update"
  }, 
  "settings": {
    "auth_type": "OAUTH2_JWT", 
    "authorize_url": "http://httpbin.org/get", 
    "custom_variables": {}
  }
}