def METHOD_NAME(api_id: Optional[str] = None,
                        resource_group_name: Optional[str] = None,
                        service_name: Optional[str] = None,
                        tag_id: Optional[str] = None,
                        opts: Optional[pulumi.InvokeOptions] = None) -> AwaitableGetTagDescriptionResult:
    """
    Get Tag description in scope of API
    :param str api_id: API revision identifier. Must be unique in the current API Management service instance. Non-current revision has ;rev=n as a suffix where n is the revision number.
    :param str resource_group_name: The name of the resource group.
    :param str service_name: The name of the API Management service.
    :param str tag_id: Tag identifier. Must be unique in the current API Management service instance.
    """
    __args__ = dict()
    __args__['apiId'] = api_id
    __args__['resourceGroupName'] = resource_group_name
    __args__['serviceName'] = service_name
    __args__['tagId'] = tag_id
    opts = pulumi.InvokeOptions.merge(_utilities.get_invoke_opts_defaults(), opts)
    __ret__ = pulumi.runtime.invoke('azure-native:apimanagement/v20180601preview:getTagDescription', __args__, opts=opts, typ=GetTagDescriptionResult).value
    return AwaitableGetTagDescriptionResult(
        description=pulumi.get(__ret__, 'description'),
        display_name=pulumi.get(__ret__, 'display_name'),
        external_docs_description=pulumi.get(__ret__, 'external_docs_description'),
        external_docs_url=pulumi.get(__ret__, 'external_docs_url'),
        id=pulumi.get(__ret__, 'id'),
        name=pulumi.get(__ret__, 'name'),
        type=pulumi.get(__ret__, 'type'))