diff --git a/.Rbuildignore b/.Rbuildignore
index e3cbc3e..9ed6386 100644
--- a/.Rbuildignore
+++ b/.Rbuildignore
@@ -4,3 +4,4 @@
 ^azkit\.code-workspace$
 ^CODEOWNERS$
 ^\.github$
+^\.lintr$
diff --git a/R/get_auth_token.R b/R/get_auth_token.R
index 52fd99e..71a7aa5 100644
--- a/R/get_auth_token.R
+++ b/R/get_auth_token.R
@@ -131,8 +131,7 @@ get_auth_token <- function(
     )
     invisible(NULL)
   } else {
-    # check_that(token, AzureAuth::is_azure_token, "Invalid token returned")
-    token
+    check_that(token, AzureAuth::is_azure_token, "Invalid token returned")
   }
 }
 
diff --git a/R/get_container.R b/R/get_container.R
index edc7331..4bbd257 100644
--- a/R/get_container.R
+++ b/R/get_container.R
@@ -1,43 +1,48 @@
 #' Get Azure storage container
 #'
-#' The environment variable "AZ_STORAGE_EP" must be set. This provides the URL
+#' The environment variable "AZ_STORAGE_EP" should be set. This provides the URL
 #'  for the default Azure storage endpoint.
 #' Use [list_container_names] to get a list of available container names.
 #'
 #' @param container_name Name of the container as a string. `NULL` by default,
 #'  which means the function will look instead for a container name stored in
 #'  the environment variable "AZ_CONTAINER"
-#' @param ... arguments to be passed through to [get_auth_token]
+#' @param token An Azure authentication token. If left as `NULL`, a token
+#'  returned by [get_auth_token] will be used
+#' @param endpoint_url An Azure endpoint URL. If left as `NULL`, the default,
+#'  the value of the environment variable "AZ_STORAGE_EP" will be used
+#' @param ... arguments to be passed through to [get_auth_token], if a token is
+#'  not already supplied
 #' @returns An Azure blob container (list object of class "blob_container")
 #' @export
-get_container <- function(container_name = NULL, ...) {
-  msg <- glue::glue(
+get_container <- function(
+  container_name = NULL,
+  token = NULL,
+  endpoint_url = NULL,
+  ...
+) {
+  msg <- paste0(
     "{.var container_name} is empty. ",
     "Did you forget to set an environment variable?"
   )
-  cont_nm <- check_nzchar(container_name, msg) %||% check_envvar("AZ_CONTAINER")
-  token <- get_auth_token(...)
-  endpoint <- get_default_endpoint(token)
-  container_names <- list_container_names(token)
-  not_found_msg <- ct_error_msg("Container {.val {cont_nm}} not found")
-  cont_nm |>
-    check_that(\(x) x %in% container_names, not_found_msg) |>
-    AzureStor::blob_container(endpoint = endpoint)
+  container_name <- (container_name %||% check_envvar("AZ_CONTAINER")) |>
+    check_nzchar(msg)
+  token <- token %||% get_auth_token(...)
+
+  get_azure_endpoint(token, endpoint_url) |>
+    AzureStor::blob_container(container_name)
 }
 
 
-#' Return a list of container names that are found at the default endpoint
+#' Return a list of container names that are found at the endpoint
 #'
 #' @inheritParams get_container
-#' @inheritParams get_default_endpoint
 #' @returns A character vector of all container names found
 #' @export
-list_container_names <- function(token = NULL, ...) {
+list_container_names <- function(token = NULL, endpoint_url = NULL, ...) {
   token <- token %||% get_auth_token(...)
-  endpoint <- get_default_endpoint(token)
-  lcn <- "list_container_names" # nolint
-  container_list <- AzureStor::list_blob_containers(endpoint) |>
-    rlang::try_fetch(error = \(e) cli::cli_abort("Error in {.fn {lcn}}: {e}"))
+  endpoint <- get_azure_endpoint(token, endpoint_url)
+  container_list <- AzureStor::list_blob_containers(endpoint)
   stopifnot("no containers found" = length(container_list) >= 1L)
   names(container_list)
 }
@@ -45,12 +50,16 @@ list_container_names <- function(token = NULL, ...) {
 
 #' Return an Azure "blob_endpoint"
 #'
-#' @param token An Azure authentication token
+#' This function will return the endpoint specified in the environment variable
+#' "AZ_STORAGE_EP" by default
+#'
+#' @inheritParams get_container
 #' @returns An Azure blob endpoint (object of class "blob_endpoint")
 #' @keywords internal
-get_default_endpoint <- function(token) {
-  check_envvar("AZ_STORAGE_EP") |>
-    AzureStor::blob_endpoint(token = token)
+get_azure_endpoint <- function(token = NULL, endpoint_url = NULL, ...) {
+  token <- token %||% get_auth_token(...)
+  endpoint_url <- endpoint_url %||% check_envvar("AZ_STORAGE_EP")
+  AzureStor::blob_endpoint(endpoint_url, token = token)
 }
 
 
diff --git a/R/read_azure_files.R b/R/read_azure_files.R
index 201ecda..b174e0d 100644
--- a/R/read_azure_files.R
+++ b/R/read_azure_files.R
@@ -129,7 +129,7 @@ check_blob_exists <- function(container, file, ext, info, path) {
   # though this usage pattern should be quite rare!
   dpath <- file.path(path, dir_name)
   fname <- basename(file)
-  if (nzchar(ext) & !gregg(fname, "\\.{ext}$")) {
+  if (nzchar(ext) && !gregg(fname, "\\.{ext}$")) {
     fname <- glue::glue("{fname}.{ext}")
   }
   # remove duplicate slashes and any initial slashes
diff --git a/man/check_scalar_type.Rd b/man/check_scalar_type.Rd
index ef9f097..7b44f15 100644
--- a/man/check_scalar_type.Rd
+++ b/man/check_scalar_type.Rd
@@ -15,7 +15,7 @@ check_scalar_type(x, type, message, pf = parent.frame())
 user if the predicate check does not succeed. Can include \code{glue}d variables
 and \code{{cli}} semantic markup.}
 
-\item{pf}{Set as \link{parent.frame} so variables in the caller environment can
+\item{pf}{Set as \code{\link[=parent.frame]{parent.frame()}} so variables in the caller environment can
 be used in the custom error message.}
 }
 \description{
diff --git a/man/check_vec.Rd b/man/check_vec.Rd
index ea4698b..4663939 100644
--- a/man/check_vec.Rd
+++ b/man/check_vec.Rd
@@ -30,7 +30,7 @@ predicate. "none" can be used to generate an inverse predicate, or the
 situation where success means that none of the elements of x satisfies the
 predicate. "some" is unlikely to be useful often, but it is available.}
 
-\item{pf}{Set as \link{parent.frame} so variables in the caller environment can
+\item{pf}{Set as \code{\link[=parent.frame]{parent.frame()}} so variables in the caller environment can
 be used in the custom error message.}
 }
 \description{
diff --git a/man/get_azure_endpoint.Rd b/man/get_azure_endpoint.Rd
new file mode 100644
index 0000000..d1d4be7
--- /dev/null
+++ b/man/get_azure_endpoint.Rd
@@ -0,0 +1,26 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/get_container.R
+\name{get_azure_endpoint}
+\alias{get_azure_endpoint}
+\title{Return an Azure "blob_endpoint"}
+\usage{
+get_azure_endpoint(token = NULL, endpoint_url = NULL, ...)
+}
+\arguments{
+\item{token}{An Azure authentication token. If left as \code{NULL}, a token
+returned by \link{get_auth_token} will be used}
+
+\item{endpoint_url}{An Azure endpoint URL. If left as \code{NULL}, the default,
+the value of the environment variable "AZ_STORAGE_EP" will be used}
+
+\item{...}{arguments to be passed through to \link{get_auth_token}, if a token is
+not already supplied}
+}
+\value{
+An Azure blob endpoint (object of class "blob_endpoint")
+}
+\description{
+This function will return the endpoint specified in the environment variable
+"AZ_STORAGE_EP" by default
+}
+\keyword{internal}
diff --git a/man/get_container.Rd b/man/get_container.Rd
index 7fe762a..6e88a05 100644
--- a/man/get_container.Rd
+++ b/man/get_container.Rd
@@ -4,20 +4,27 @@
 \alias{get_container}
 \title{Get Azure storage container}
 \usage{
-get_container(container_name = NULL, ...)
+get_container(container_name = NULL, token = NULL, endpoint_url = NULL, ...)
 }
 \arguments{
 \item{container_name}{Name of the container as a string. \code{NULL} by default,
 which means the function will look instead for a container name stored in
 the environment variable "AZ_CONTAINER"}
 
-\item{...}{arguments to be passed through to \link{get_auth_token}}
+\item{token}{An Azure authentication token. If left as \code{NULL}, a token
+returned by \link{get_auth_token} will be used}
+
+\item{endpoint_url}{An Azure endpoint URL. If left as \code{NULL}, the default,
+the value of the environment variable "AZ_STORAGE_EP" will be used}
+
+\item{...}{arguments to be passed through to \link{get_auth_token}, if a token is
+not already supplied}
 }
 \value{
 An Azure blob container (list object of class "blob_container")
 }
 \description{
-The environment variable "AZ_STORAGE_EP" must be set. This provides the URL
+The environment variable "AZ_STORAGE_EP" should be set. This provides the URL
 for the default Azure storage endpoint.
 Use \link{list_container_names} to get a list of available container names.
 }
diff --git a/man/get_default_endpoint.Rd b/man/get_default_endpoint.Rd
deleted file mode 100644
index 7e76e8f..0000000
--- a/man/get_default_endpoint.Rd
+++ /dev/null
@@ -1,18 +0,0 @@
-% Generated by roxygen2: do not edit by hand
-% Please edit documentation in R/get_container.R
-\name{get_default_endpoint}
-\alias{get_default_endpoint}
-\title{Return an Azure "blob_endpoint"}
-\usage{
-get_default_endpoint(token)
-}
-\arguments{
-\item{token}{An Azure authentication token}
-}
-\value{
-An Azure blob endpoint (object of class "blob_endpoint")
-}
-\description{
-Return an Azure "blob_endpoint"
-}
-\keyword{internal}
diff --git a/man/list_container_names.Rd b/man/list_container_names.Rd
index 814b723..3587268 100644
--- a/man/list_container_names.Rd
+++ b/man/list_container_names.Rd
@@ -2,18 +2,23 @@
 % Please edit documentation in R/get_container.R
 \name{list_container_names}
 \alias{list_container_names}
-\title{Return a list of container names that are found at the default endpoint}
+\title{Return a list of container names that are found at the endpoint}
 \usage{
-list_container_names(token = NULL, ...)
+list_container_names(token = NULL, endpoint_url = NULL, ...)
 }
 \arguments{
-\item{token}{An Azure authentication token}
+\item{token}{An Azure authentication token. If left as \code{NULL}, a token
+returned by \link{get_auth_token} will be used}
 
-\item{...}{arguments to be passed through to \code{\link[=get_auth_token]{get_auth_token()}}}
+\item{endpoint_url}{An Azure endpoint URL. If left as \code{NULL}, the default,
+the value of the environment variable "AZ_STORAGE_EP" will be used}
+
+\item{...}{arguments to be passed through to \link{get_auth_token}, if a token is
+not already supplied}
 }
 \value{
 A character vector of all container names found
 }
 \description{
-Return a list of container names that are found at the default endpoint
+Return a list of container names that are found at the endpoint
 }
diff --git a/man/read_azure_csv.Rd b/man/read_azure_csv.Rd
index cccbb65..29f55ed 100644
--- a/man/read_azure_csv.Rd
+++ b/man/read_azure_csv.Rd
@@ -24,7 +24,7 @@ container) by default.}
 being read. Useful for checking the function is doing what is expected, but
 can be turned off with \code{FALSE}. Can be set persistently with the option
 "azkit.info". If \code{NULL} then it will default to the value of
-\link[rlang:is_interactive]{rlang::is_interactive} (ie \code{TRUE} for interactive sessions).}
+\link[rlang:is_interactive]{rlang::is_interactive} (that is, \code{TRUE} for interactive sessions).}
 
 \item{...}{optional arguments to be passed through to \link[readr:read_delim]{readr::read_delim}}
 }
diff --git a/man/read_azure_file.Rd b/man/read_azure_file.Rd
index 5cb50da..eaa51ea 100644
--- a/man/read_azure_file.Rd
+++ b/man/read_azure_file.Rd
@@ -24,7 +24,7 @@ container) by default.}
 being read. Useful for checking the function is doing what is expected, but
 can be turned off with \code{FALSE}. Can be set persistently with the option
 "azkit.info". If \code{NULL} then it will default to the value of
-\link[rlang:is_interactive]{rlang::is_interactive} (ie \code{TRUE} for interactive sessions).}
+\link[rlang:is_interactive]{rlang::is_interactive} (that is, \code{TRUE} for interactive sessions).}
 
 \item{ext}{If a custom extension needs to be supplied, you can specify it
 here. If \code{NULL}, the default, the extension of \code{file} will be used}
diff --git a/man/read_azure_json.Rd b/man/read_azure_json.Rd
index 1fe47d2..2df1630 100644
--- a/man/read_azure_json.Rd
+++ b/man/read_azure_json.Rd
@@ -24,7 +24,7 @@ container) by default.}
 being read. Useful for checking the function is doing what is expected, but
 can be turned off with \code{FALSE}. Can be set persistently with the option
 "azkit.info". If \code{NULL} then it will default to the value of
-\link[rlang:is_interactive]{rlang::is_interactive} (ie \code{TRUE} for interactive sessions).}
+\link[rlang:is_interactive]{rlang::is_interactive} (that is, \code{TRUE} for interactive sessions).}
 
 \item{...}{optional arguments to be passed through to
 \link[yyjsonr:read_json_raw]{yyjsonr::read_json_raw}}
diff --git a/man/read_azure_jsongz.Rd b/man/read_azure_jsongz.Rd
index a8e3bdc..b44a541 100644
--- a/man/read_azure_jsongz.Rd
+++ b/man/read_azure_jsongz.Rd
@@ -24,7 +24,7 @@ container) by default.}
 being read. Useful for checking the function is doing what is expected, but
 can be turned off with \code{FALSE}. Can be set persistently with the option
 "azkit.info". If \code{NULL} then it will default to the value of
-\link[rlang:is_interactive]{rlang::is_interactive} (ie \code{TRUE} for interactive sessions).}
+\link[rlang:is_interactive]{rlang::is_interactive} (that is, \code{TRUE} for interactive sessions).}
 
 \item{...}{optional arguments to be passed through to
 \link[yyjsonr:read_json_file]{yyjsonr::read_json_file}}
diff --git a/man/read_azure_parquet.Rd b/man/read_azure_parquet.Rd
index 39e6954..2bee797 100644
--- a/man/read_azure_parquet.Rd
+++ b/man/read_azure_parquet.Rd
@@ -24,7 +24,7 @@ container) by default.}
 being read. Useful for checking the function is doing what is expected, but
 can be turned off with \code{FALSE}. Can be set persistently with the option
 "azkit.info". If \code{NULL} then it will default to the value of
-\link[rlang:is_interactive]{rlang::is_interactive} (ie \code{TRUE} for interactive sessions).}
+\link[rlang:is_interactive]{rlang::is_interactive} (that is, \code{TRUE} for interactive sessions).}
 
 \item{...}{optional arguments to be passed through to \link[arrow:read_parquet]{arrow::read_parquet}}
 }
diff --git a/man/read_azure_rds.Rd b/man/read_azure_rds.Rd
index 7a6a5d3..c099418 100644
--- a/man/read_azure_rds.Rd
+++ b/man/read_azure_rds.Rd
@@ -24,7 +24,7 @@ container) by default.}
 being read. Useful for checking the function is doing what is expected, but
 can be turned off with \code{FALSE}. Can be set persistently with the option
 "azkit.info". If \code{NULL} then it will default to the value of
-\link[rlang:is_interactive]{rlang::is_interactive} (ie \code{TRUE} for interactive sessions).}
+\link[rlang:is_interactive]{rlang::is_interactive} (that is, \code{TRUE} for interactive sessions).}
 }
 \value{
 Data object that was stored in the rds file