diff --git a/src/rest/extensions/commissioner_allow_list.cpp b/src/rest/extensions/commissioner_allow_list.cpp
index 00c69979ff4..0407945396d 100644
--- a/src/rest/extensions/commissioner_allow_list.cpp
+++ b/src/rest/extensions/commissioner_allow_list.cpp
@@ -57,6 +57,7 @@ extern "C" {
 #define COMMISSIONER_START_WAIT_TIME_MS 100
 #define COMMISSIONER_START_MAX_ATTEMPTS 5
 
+static otInstance                            *mInstance;
 static allow_list::LinkedList<AllowListEntry> AllowListEntryList;
 static void                                   consoleEntryPrint(AllowListEntry *aEntry);
 
@@ -104,11 +105,11 @@ AllowListEntry *entryEui64Find(const otExtAddress *aEui64)
     return entry;
 }
 
-otError allowListCommissionerJoinerAdd(otExtAddress aEui64,
-                                       uint32_t     aTimeout,
-                                       char        *aPskd,
-                                       otInstance  *aInstance,
-                                       uuid_t       uuid)
+otError allowListCommissionerJoinerAdd(otExtAddress       aEui64,
+                                       uint32_t           aTimeout,
+                                       char              *aPskd,
+                                       otInstance        *aInstance,
+                                       otbr::rest::uuid_t uuid)
 {
     otError             error;
     AllowListEntry     *entry   = nullptr;
@@ -197,8 +198,8 @@ AllowListEntry *parse_buf_as_json(char *aBuf)
     otExtAddress                        eui64;
     uint32_t                            timeout = 0;
     AllowListEntry::AllowListEntryState state   = AllowListEntry::kAllowListEntryNew;
-    UUID                                uuid_obj;
-    uuid_t                              uuid;
+    otbr::rest::UUID                    uuid_obj;
+    otbr::rest::uuid_t                  uuid;
     char                               *uuid_str     = nullptr;
     char                               *eui64_str    = nullptr;
     char                               *pskdValue    = nullptr;
@@ -274,10 +275,10 @@ AllowListEntry *parse_buf_as_json(char *aBuf)
     return pEntry;
 }
 
-void allowListAddDevice(otExtAddress aEui64, uint32_t aTimeout, char *aPskd, uuid_t aUuid)
+void allowListAddDevice(otExtAddress aEui64, uint32_t aTimeout, char *aPskd, otbr::rest::uuid_t aUuid)
 {
     assert(nullptr != aPskd);
-
+    otError         error;
     AllowListEntry *pEntry = entryEui64Find(&aEui64);
 
     int   pskd_len = strlen(aPskd);
@@ -294,19 +295,18 @@ void allowListAddDevice(otExtAddress aEui64, uint32_t aTimeout, char *aPskd, uui
     }
     else
     {
-        // TODO if (aUuid == NULL)
-        //{
-        //     //  this may not be needed
-        //     uuid_generate_random(&aUuid);
-        // }
         pEntry = new AllowListEntry(aEui64, aUuid, aTimeout, pskd_new);
         if (nullptr == pEntry)
         {
-            //  otbrLogErr("%s: Err creating a new AllowListEntry", __func__);
+            otbrLogErr("%s: Err creating a new AllowListEntry", __func__);
             free(pskd_new);
             return;
         }
-        AllowListEntryList.Add(*pEntry);
+        error = AllowListEntryList.Add(*pEntry);
+        if (error != OT_ERROR_NONE)
+        {
+            otbrLogWarning("%s: already have AllowListEntry", __func__);
+        }
     }
 
     consoleEntryPrint(pEntry);
@@ -322,7 +322,7 @@ static void consoleEntryPrint(AllowListEntry *aEntry)
     assert(nullptr != aEntry);
     // char uuidStr[UUID_STR_LEN] = {0};
 
-    UUID uuid_obj = UUID();
+    otbr::rest::UUID uuid_obj = otbr::rest::UUID();
     uuid_obj.setUuid(aEntry->muuid);
 
     // uuid_unparse(aEntry->muuid, uuidStr);
@@ -432,7 +432,7 @@ uint8_t allowListGetPendingJoinersCount(void)
 
     while (entry)
     {
-        if ((AllowListEntry::kAllowListEntryJoined != entry->mstate) ||
+        if ((AllowListEntry::kAllowListEntryJoined != entry->mstate) &&
             (AllowListEntry::kAllowListEntryJoinFailed != entry->mstate))
         {
             pendingJoinersCount++;
@@ -454,6 +454,8 @@ void HandleJoinerEvent(otCommissionerJoinerEvent aEvent,
     AllowListEntry *entry               = nullptr;
     uint8_t         pendingDevicesCount = 0;
 
+    otError error = OT_ERROR_NONE;
+
     // @note: Thread may call this for joiners that we are not supposed to join
     //        do not assume `entry` is not null in the rest of the code.
     entry = entryEui64Find(&aJoinerInfo->mSharedId.mEui64);
@@ -510,7 +512,8 @@ void HandleJoinerEvent(otCommissionerJoinerEvent aEvent,
         // If all entries have been attempted and nothing is pending, stop the commissioner
         if (0 == pendingDevicesCount)
         {
-            allowListCommissionerStopPost();
+            error = allowListCommissionerStopPost();
+            otbrLogWarning("Commissioner Stop: %s", otThreadErrorToString(error));
         }
         else
         {
@@ -525,6 +528,7 @@ void HandleJoinerEvent(otCommissionerJoinerEvent aEvent,
 otError allowListCommissionerStart(otInstance *aInstance)
 {
     otError error = OT_ERROR_FAILED;
+    mInstance     = aInstance;
 
     error = otCommissionerStart(aInstance, &HandleStateChanged, &HandleJoinerEvent, NULL);
 
@@ -533,33 +537,29 @@ otError allowListCommissionerStart(otInstance *aInstance)
 
 otError allowListCommissionerStopPost(void)
 {
-    return OT_ERROR_NONE;
+    otError error = OT_ERROR_FAILED;
+
+    error = otCommissionerStop(mInstance);
+
+    return error;
 }
 
 cJSON *AllowListEntry::Allow_list_entry_as_CJSON(const char *entryType)
 {
     assert(nullptr != entryType);
 
-    cJSON *entry_json_obj = nullptr;
-    // cJSON *hasActivationKey    = nullptr;
+    cJSON *entry_json_obj      = nullptr;
     cJSON *attributes_json_obj = nullptr;
     char   eui64_str[17]       = {0};
-    // char   uuid_str[UUID_STR_LEN] = {0};
-
-    UUID uuid_obj = UUID();
 
-    // hasActivationKey = cJSON_CreateObject();
+    otbr::rest::UUID uuid_obj = otbr::rest::UUID();
 
-    memset(eui64_str, 0, sizeof(eui64_str));
-    sprintf(eui64_str, "%02x%02x%02x%02x%02x%02x%02x%02x", meui64.m8[0], meui64.m8[1], meui64.m8[2], meui64.m8[3],
-            meui64.m8[4], meui64.m8[5], meui64.m8[6], meui64.m8[7]);
+    snprintf(eui64_str, sizeof(eui64_str), "%02x%02x%02x%02x%02x%02x%02x%02x", meui64.m8[0], meui64.m8[1], meui64.m8[2],
+             meui64.m8[3], meui64.m8[4], meui64.m8[5], meui64.m8[6], meui64.m8[7]);
 
-    // memset(uuid_str, 0, sizeof(uuid_str));
-    // uuid_unparse(muuid, uuid_str);
     uuid_obj.setUuid(muuid);
 
     attributes_json_obj = cJSON_CreateObject();
-    // cJSON_AddItemToObject(attributes_json_obj, "hasActivationKey", hasActivationKey);
     cJSON_AddItemToObject(attributes_json_obj, "eui", cJSON_CreateString(eui64_str));
     cJSON_AddItemToObject(attributes_json_obj, "pskd", cJSON_CreateString(mPSKd));
 
diff --git a/src/rest/extensions/commissioner_allow_list.hpp b/src/rest/extensions/commissioner_allow_list.hpp
index b588b74dc46..34647588269 100644
--- a/src/rest/extensions/commissioner_allow_list.hpp
+++ b/src/rest/extensions/commissioner_allow_list.hpp
@@ -91,7 +91,7 @@ class AllowListEntry : public allow_list::LinkedListEntry<AllowListEntry>
     /**
      * This constructor creates an AllowListEntry.
      */
-    AllowListEntry(otExtAddress aEui64, uuid_t uuid, uint32_t aTimeout, char *aPskd)
+    AllowListEntry(otExtAddress aEui64, otbr::rest::uuid_t uuid, uint32_t aTimeout, char *aPskd)
     {
         meui64   = aEui64;
         muuid    = uuid;
@@ -101,7 +101,11 @@ class AllowListEntry : public allow_list::LinkedListEntry<AllowListEntry>
         mNext    = nullptr;
     }
 
-    AllowListEntry(otExtAddress aEui64, uuid_t uuid, uint32_t aTimeout, AllowListEntryState state, char *aPskd)
+    AllowListEntry(otExtAddress        aEui64,
+                   otbr::rest::uuid_t  uuid,
+                   uint32_t            aTimeout,
+                   AllowListEntryState state,
+                   char               *aPskd)
     {
         meui64   = aEui64;
         muuid    = uuid;
@@ -136,7 +140,7 @@ class AllowListEntry : public allow_list::LinkedListEntry<AllowListEntry>
 
     // Members
     otExtAddress        meui64;
-    uuid_t              muuid;
+    otbr::rest::uuid_t  muuid;
     uint32_t            mTimeout;
     char               *mPSKd;
     AllowListEntryState mstate;
@@ -180,11 +184,11 @@ bool eui64IsNull(const otExtAddress aEui64);
  * is not set. OT_ERROR_INVALID_STATE On-Mesh commissioner is not active.
  *
  */
-otError allowListCommissionerJoinerAdd(otExtAddress aEui64,
-                                       uint32_t     aTimeout,
-                                       char        *aPskd,
-                                       otInstance  *aInstance,
-                                       uuid_t       uuid);
+otError allowListCommissionerJoinerAdd(otExtAddress       aEui64,
+                                       uint32_t           aTimeout,
+                                       char              *aPskd,
+                                       otInstance        *aInstance,
+                                       otbr::rest::uuid_t uuid);
 
 /**
  * @brief Remove a single entry from On-Mesh commissioner joiner table
@@ -216,7 +220,7 @@ otError allowListEntryErase(otExtAddress aEui64);
  * automatically removed, in seconds.
  * @param[in]  aPskd Pskd to use when joinig the device
  */
-void allowListAddDevice(otExtAddress aEui64, uint32_t aTimeout, char *aPskd, uuid_t uuid);
+void allowListAddDevice(otExtAddress aEui64, uint32_t aTimeout, char *aPskd, otbr::rest::uuid_t uuid);
 
 /**
  * @brief    Print Allow List Entries available in memory to console
@@ -270,4 +274,4 @@ otError allowListEntryJoinStatusGet(const otExtAddress *eui64);
 }
 #endif
 
-#endif /* EXTENSIONS_COMMISSIONER_ALLOW_LIST_HPP_ */
+#endif // EXTENSIONS_COMMISSIONER_ALLOW_LIST_HPP_
diff --git a/src/rest/extensions/rest_server_common.cpp b/src/rest/extensions/rest_server_common.cpp
index bf5baf9de07..e36c0777867 100644
--- a/src/rest/extensions/rest_server_common.cpp
+++ b/src/rest/extensions/rest_server_common.cpp
@@ -32,11 +32,13 @@
  */
 #include "rest_server_common.hpp"
 
+namespace otbr {
+namespace rest {
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-#include <cJSON.h>
 #include <ctype.h>
 #include <openthread/logging.h>
 
@@ -59,7 +61,7 @@ void combineMeshLocalPrefixAndIID(const otMeshLocalPrefix        *meshLocalPrefi
 }
 
 // count number of 1s in bitmask
-int my_count_ones(uint32_t bitmask)
+int count_ones(uint32_t bitmask)
 {
     int count = 0;
     while (bitmask)
@@ -166,3 +168,6 @@ bool is_hex_string(char *str)
 #ifdef __cplusplus
 }
 #endif
+
+} // namespace rest
+} // namespace otbr
diff --git a/src/rest/extensions/rest_server_common.hpp b/src/rest/extensions/rest_server_common.hpp
index be2ec1911dd..37fd4d54d9c 100644
--- a/src/rest/extensions/rest_server_common.hpp
+++ b/src/rest/extensions/rest_server_common.hpp
@@ -35,6 +35,9 @@
 
 #include "utils/thread_helper.hpp"
 
+namespace otbr {
+namespace rest {
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -64,7 +67,7 @@ void combineMeshLocalPrefixAndIID(const otMeshLocalPrefix        *meshLocalPrefi
                                   otIp6Address                   *ip6Address);
 
 // count number of 1s in bitmask
-int my_count_ones(uint32_t bitmask);
+int count_ones(uint32_t bitmask);
 
 uint8_t joiner_verify_pskd(char *pskd);
 
@@ -94,4 +97,7 @@ bool is_hex_string(char *str);
 } // end of extern "C"
 #endif
 
-#endif
+} // namespace rest
+} // namespace otbr
+
+#endif // REST_SERVER_COMMON_HPP_
diff --git a/src/rest/extensions/rest_task_add_thread_device.cpp b/src/rest/extensions/rest_task_add_thread_device.cpp
index f60ede8ccc0..8f67c4b29f7 100644
--- a/src/rest/extensions/rest_task_add_thread_device.cpp
+++ b/src/rest/extensions/rest_task_add_thread_device.cpp
@@ -57,6 +57,7 @@ uint32_t getJoinerExpirationTime(otExtAddress *aEui);
 cJSON *jsonify_add_thread_device_task(task_node_t *task_node)
 {
     otExtAddress eui64 = {0};
+    otError      error = OT_ERROR_NONE;
 
     cJSON *task_json  = task_node_to_json(task_node);
     cJSON *attributes = cJSON_GetObjectItemCaseSensitive(task_json, "attributes");
@@ -66,7 +67,7 @@ cJSON *jsonify_add_thread_device_task(task_node_t *task_node)
     if ((task_node->status > ACTIONS_TASK_STATUS_PENDING) && (task_node->status != ACTIONS_TASK_STATUS_UNIMPLEMENTED))
     {
         // find allowListEntry and get more detailed status
-        str_to_m8(eui64.m8, eui->valuestring, OT_EXT_ADDRESS_SIZE);
+        SuccessOrExit(error = otbr::rest::str_to_m8(eui64.m8, eui->valuestring, OT_EXT_ADDRESS_SIZE));
 
         if (entryEui64Find(&eui64) != nullptr)
         {
@@ -81,6 +82,12 @@ cJSON *jsonify_add_thread_device_task(task_node_t *task_node)
                            cJSON_Print(attributes));
         }
     }
+exit:
+    if (error != OT_ERROR_NONE)
+    {
+        otbrLogWarning("%s:%d - %s - missing or bad value in a field: %s", __FILE__, __LINE__, __func__,
+                       cJSON_Print(attributes));
+    }
     return task_json;
 }
 
@@ -95,14 +102,15 @@ uint8_t validate_add_thread_device_task(cJSON *attributes)
 
     VerifyOrExit((NULL != timeout && cJSON_IsNumber(timeout)), error = OT_ERROR_FAILED);
 
-    VerifyOrExit(
-        (NULL != eui && cJSON_IsString(eui) && 16 == strlen(eui->valuestring) && is_hex_string(eui->valuestring)),
-        error = OT_ERROR_FAILED);
+    VerifyOrExit((NULL != eui && cJSON_IsString(eui) && 16 == strlen(eui->valuestring) &&
+                  otbr::rest::is_hex_string(eui->valuestring)),
+                 error = OT_ERROR_FAILED);
     // check eui is convertable
-    SuccessOrExit(error = str_to_m8(eui64.m8, eui->valuestring, OT_EXT_ADDRESS_SIZE));
+    SuccessOrExit(error = otbr::rest::str_to_m8(eui64.m8, eui->valuestring, OT_EXT_ADDRESS_SIZE));
 
-    VerifyOrExit((NULL != pskd && cJSON_IsString(pskd) && (WPANSTATUS_OK == joiner_verify_pskd(pskd->valuestring))),
-                 error = OT_ERROR_FAILED);
+    VerifyOrExit(
+        (NULL != pskd && cJSON_IsString(pskd) && (WPANSTATUS_OK == otbr::rest::joiner_verify_pskd(pskd->valuestring))),
+        error = OT_ERROR_FAILED);
 
 exit:
     if (error != OT_ERROR_NONE)
@@ -128,7 +136,7 @@ otError addJoiner(task_node_t *task_node, otInstance *aInstance)
     cJSON *pskd       = cJSON_GetObjectItemCaseSensitive(attributes, ATTRIBUTE_PSKD);
     cJSON *timeout    = cJSON_GetObjectItemCaseSensitive(attributes, "timeout");
 
-    str_to_m8(eui64.m8, eui->valuestring, OT_EXT_ADDRESS_SIZE);
+    SuccessOrExit(error = otbr::rest::str_to_m8(eui64.m8, eui->valuestring, OT_EXT_ADDRESS_SIZE));
 
     if ((entryEui64Find(&eui64) != NULL) &&
         (entryEui64Find(&eui64)->mstate < AllowListEntry::kAllowListEntryJoinFailed))
@@ -231,7 +239,7 @@ rest_actions_task_result_t evaluate_add_thread_device_task(task_node_t *task_nod
     cJSON *attributes = cJSON_GetObjectItemCaseSensitive(task, "attributes");
     cJSON *eui        = cJSON_GetObjectItemCaseSensitive(attributes, "eui");
 
-    str_to_m8(eui64.m8, eui->valuestring, OT_EXT_ADDRESS_SIZE);
+    SuccessOrExit(error = otbr::rest::str_to_m8(eui64.m8, eui->valuestring, OT_EXT_ADDRESS_SIZE));
 
     addrPtr = &eui64;
     SuccessOrExit(error = allowListEntryJoinStatusGet(addrPtr));
@@ -259,7 +267,7 @@ rest_actions_task_result_t clean_add_thread_device_task(task_node_t *task_node,
     otError error = OT_ERROR_NONE;
 
     otExtAddress eui64 = {0};
-    str_to_m8(eui64.m8, eui->valuestring, OT_EXT_ADDRESS_SIZE);
+    SuccessOrExit(error = otbr::rest::str_to_m8(eui64.m8, eui->valuestring, OT_EXT_ADDRESS_SIZE));
 
     SuccessOrExit(error = allowListCommissionerJoinerRemove(eui64, aInstance));
     SuccessOrExit(error = allowListEntryErase(eui64));
diff --git a/src/rest/extensions/rest_task_add_thread_device.hpp b/src/rest/extensions/rest_task_add_thread_device.hpp
index 187fafdeeb5..7e922b2699c 100644
--- a/src/rest/extensions/rest_task_add_thread_device.hpp
+++ b/src/rest/extensions/rest_task_add_thread_device.hpp
@@ -37,6 +37,7 @@
 #include "rest_task_handler.hpp"
 #include "rest_task_queue.hpp"
 
+// Forward declare cJSON in the global scope
 struct cJSON;
 
 #ifdef __cplusplus
diff --git a/src/rest/extensions/rest_task_handler.cpp b/src/rest/extensions/rest_task_handler.cpp
index 8e1f6ec909f..79d99aa007e 100644
--- a/src/rest/extensions/rest_task_handler.cpp
+++ b/src/rest/extensions/rest_task_handler.cpp
@@ -31,6 +31,8 @@
  *          update task status and conversion of `task_node` to `JSON` format.
  *
  */
+#include <assert.h>
+
 #include "rest_task_handler.hpp"
 #include "rest_task_queue.hpp"
 #include "uuid.hpp"
@@ -61,7 +63,7 @@ task_node_t *task_node_new(cJSON *task)
     task_node_t *task_node = (task_node_t *)calloc(1, sizeof(task_node_t)); // free in rest_task_queue_handle on delete
     assert(NULL != task_node);
 
-    UUID uuid = UUID();
+    otbr::rest::UUID uuid = otbr::rest::UUID();
 
     // Duplicate the client data associated with this task
     task_node->task = cJSON_Duplicate(task, cJSON_True);
@@ -75,7 +77,7 @@ task_node_t *task_node_new(cJSON *task)
     // Populate UUID
     uuid.generateRandom();
     uuid.getUuid(task_node->id);
-    snprintf(task_node->id_str, sizeof(task_node->id_str), uuid.toString().c_str());
+    snprintf(task_node->id_str, sizeof(task_node->id_str), "%s", uuid.toString().c_str());
     otbrLogWarning("creating new task with id %s", task_node->id_str);
     cJSON_AddStringToObject(task_node->task, "id", task_node->id_str);
 
diff --git a/src/rest/extensions/rest_task_handler.hpp b/src/rest/extensions/rest_task_handler.hpp
index 2bf41e5b767..1f39e935d5f 100644
--- a/src/rest/extensions/rest_task_handler.hpp
+++ b/src/rest/extensions/rest_task_handler.hpp
@@ -36,6 +36,7 @@
 
 #include "uuid.hpp"
 
+// Forward declare cJSON in the global scope
 struct cJSON;
 
 #ifdef __cplusplus
@@ -98,14 +99,14 @@ typedef enum
 typedef struct relationship
 {
     char mType[MAX_TYPELENGTH];
-    char mId[UUID_STR_LEN];
+    char mId[otbr::rest::UUID_STR_LEN];
 } relationship_t;
 
 typedef struct task_node_s
 {
     cJSON                     *task;
-    uuid_t                     id;
-    char                       id_str[UUID_STR_LEN];
+    otbr::rest::uuid_t         id;
+    char                       id_str[otbr::rest::UUID_STR_LEN];
     rest_actions_task_t        type;
     rest_actions_task_status_t status;
     int                        created;
@@ -159,4 +160,4 @@ bool can_remove_task(task_node_t *aTaskNode);
 } // end of extern "C"
 #endif
 
-#endif
+#endif // REST_TASK_HANDLER_HPP_
diff --git a/src/rest/extensions/rest_task_queue.cpp b/src/rest/extensions/rest_task_queue.cpp
index d1f0019f04a..51bfd0b8cd2 100644
--- a/src/rest/extensions/rest_task_queue.cpp
+++ b/src/rest/extensions/rest_task_queue.cpp
@@ -115,12 +115,12 @@ cJSON *task_to_json(task_node_t *aTaskNode)
     return handlers->jsonify(aTaskNode);
 }
 
-task_node_t *task_node_find_by_id(uuid_t uuid)
+task_node_t *task_node_find_by_id(otbr::rest::uuid_t uuid)
 {
     task_node_t *head = task_queue;
     while (NULL != head)
     {
-        if (uuid_equals(uuid, head->id))
+        if (otbr::rest::uuid_equals(uuid, head->id))
         {
             return head;
         }
@@ -226,7 +226,7 @@ uint8_t validate_task(cJSON *task)
     return ACTIONS_TASK_INVALID;
 }
 
-bool queue_task(cJSON *task, uuid_t *task_id)
+bool queue_task(cJSON *task, otbr::rest::uuid_t *task_id)
 {
     otbrLogWarning("Queueing task: %s", cJSON_PrintUnformatted(task));
     if (TASK_QUEUE_MAX <= task_queue_len)
@@ -244,7 +244,7 @@ bool queue_task(cJSON *task, uuid_t *task_id)
     }
     // Generate the task object, and copy the ID to the output
     task_node_t *task_node = task_node_new(task);
-    memcpy(task_id, &(task_node->id), sizeof(uuid_t));
+    memcpy(task_id, &(task_node->id), sizeof(otbr::rest::uuid_t));
 
     if (NULL == task_queue)
     {
@@ -485,10 +485,6 @@ void rest_task_queue_handle(void)
         // Get ready to process the next task in the queue
         head = head->next;
     }
-    // otbrLogWarning("EXITING rest_task_queue_task");
-    // pthread_exit(NULL);
-
-    // return NULL;
 }
 
 void rest_task_queue_task_init(otInstance *aInstance)
@@ -506,11 +502,9 @@ void rest_task_queue_task_init(otInstance *aInstance)
     //
     // This check iterates over the list an ensures that each entry has a
     // type_id which is exactly 1 greater than the previous entry.
-    rest_actions_task_t previous_id = handlers[0].type_id;
     for (size_t idx = 1; idx < ARRAY_SIZE(handlers); idx++)
     {
-        assert(previous_id + 1 == handlers[idx].type_id);
-        previous_id = handlers[idx].type_id;
+        assert(handlers[idx - 1].type_id + 1 == handlers[idx].type_id);
     }
 }
 
diff --git a/src/rest/extensions/rest_task_queue.hpp b/src/rest/extensions/rest_task_queue.hpp
index adeb3fed8a7..5804ea44cad 100644
--- a/src/rest/extensions/rest_task_queue.hpp
+++ b/src/rest/extensions/rest_task_queue.hpp
@@ -37,6 +37,7 @@
 #include "rest_task_handler.hpp"
 #include "utils/thread_helper.hpp"
 
+// Forward declare cJSON in the global scope
 struct cJSON;
 
 #ifdef __cplusplus
@@ -141,13 +142,13 @@ uint8_t validate_task(cJSON *task);
  *        be proccessed on different thread.
  *
  * @param task A pointer to JSON array item.
- * @param uuid_t *task_id A reference to get the task_id
+ * @param task_id A reference to get the task_id
  * @return true     Task queued
  *  @return false    Not able to queue task
  */
-bool         queue_task(cJSON *task, uuid_t *task_id);
+bool         queue_task(cJSON *task, otbr::rest::uuid_t *task_id);
 cJSON       *task_to_json(task_node_t *task_node);
-task_node_t *task_node_find_by_id(uuid_t uuid);
+task_node_t *task_node_find_by_id(otbr::rest::uuid_t uuid);
 
 /**
  * @brief When called, I generate a CJSON object for the task metadata
@@ -203,4 +204,4 @@ bool task_type_id_from_name(const char *task_name, rest_actions_task_t *type_id)
 } // end of extern "C"
 #endif
 
-#endif
+#endif // REST_TASK_QUEUE_HPP_
diff --git a/src/rest/extensions/timestamp.cpp b/src/rest/extensions/timestamp.cpp
index 3fe9ad38efa..cbad58e95b7 100644
--- a/src/rest/extensions/timestamp.cpp
+++ b/src/rest/extensions/timestamp.cpp
@@ -37,6 +37,9 @@
 using namespace std;
 using namespace std::chrono;
 
+namespace otbr {
+namespace rest {
+
 std::string now_rfc3339()
 {
     return toRfc3339(system_clock::now());
@@ -81,3 +84,6 @@ std::string toRfc3339(system_clock::time_point timepoint)
 
     return std::string(updated_str);
 }
+
+} // namespace rest
+} // namespace otbr
diff --git a/src/rest/extensions/timestamp.hpp b/src/rest/extensions/timestamp.hpp
index 6d93b8069f9..1ed8998624b 100644
--- a/src/rest/extensions/timestamp.hpp
+++ b/src/rest/extensions/timestamp.hpp
@@ -26,11 +26,22 @@
  *  POSSIBILITY OF SUCH DAMAGE.
  */
 
+#ifndef TIMESTAMP_HPP
+#define TIMESTAMP_HPP
+
 #include <chrono>
 #include <string>
 
+namespace otbr {
+namespace rest {
+
 std::string now_rfc3339();
 
 // std::string toRfc3339Utc(std::chrono::system_clock::time_point timepoint);
 
 std::string toRfc3339(std::chrono::system_clock::time_point timepoint);
+
+} // namespace rest
+} // namespace otbr
+
+#endif // TIMESTAMP_HPP
diff --git a/src/rest/extensions/uuid.cpp b/src/rest/extensions/uuid.cpp
index a78868a5e47..994ae051c1a 100644
--- a/src/rest/extensions/uuid.cpp
+++ b/src/rest/extensions/uuid.cpp
@@ -36,6 +36,9 @@
 #include <random>
 #include <sstream>
 
+namespace otbr {
+namespace rest {
+
 UUID::UUID()
 {
     std::memset(&uuid, 0, sizeof(uuid));
@@ -122,3 +125,6 @@ int uuid_equals(uuid_t uuid1, uuid_t uuid2)
            uuid1.node[1] == uuid2.node[1] && uuid1.node[2] == uuid2.node[2] && uuid1.node[3] == uuid2.node[3] &&
            uuid1.node[4] == uuid2.node[4] && uuid1.node[5] == uuid2.node[5];
 }
+
+} // namespace rest
+} // namespace otbr
diff --git a/src/rest/extensions/uuid.hpp b/src/rest/extensions/uuid.hpp
index dc377ed7f52..8912ebd9c55 100644
--- a/src/rest/extensions/uuid.hpp
+++ b/src/rest/extensions/uuid.hpp
@@ -33,6 +33,9 @@
 #include <cstring>
 #include <string>
 
+namespace otbr {
+namespace rest {
+
 const int UUID_LEN     = 16;
 const int UUID_STR_LEN = 37;
 
@@ -112,4 +115,7 @@ class UUID
  */
 int uuid_equals(uuid_t uuid1, uuid_t uuid2);
 
+} // namespace rest
+} // namespace otbr
+
 #endif // UUID_HPP
diff --git a/src/rest/openapi.yaml b/src/rest/openapi.yaml
index 2ba2a4dd56f..70e5a3a2598 100644
--- a/src/rest/openapi.yaml
+++ b/src/rest/openapi.yaml
@@ -14,11 +14,201 @@ info:
 servers:
   - url: http://localhost:8081
 tags:
+  - name: Actions
+    description: Task queue.
   - name: node
     description: Thread parameters of this node.
   - name: diagnostics
     description: Thread network diagnostic.
 paths:
+  /api/actions:
+    get:
+      tags:
+        - Actions
+      summary: Read Actions collection.
+      parameters:
+        - name: Accept
+          description: Must be set to `application/vnd.api+json`
+          in: header
+          required: true
+          schema:
+            type: string
+            example: application/vnd.api+json
+      responses:
+        "200":
+          description: List of actions.
+          content:
+            application/vnd.api+json:
+              schema:
+                type: object
+              example:
+                data:
+                  - id: 9ecae480-07a0-4b72-869d-15858196144e
+                    type: addThreadDeviceTask
+                    attributes:
+                      eui: "fedcba9876543210"
+                      pskd: "J01NME"
+                      timeout: 888
+                      status: "pending"
+                  - id: 9ecae480-07a0-4b72-869d-15858196144f
+                    type: addThreadDeviceTask
+                    attributes:
+                      eui: "fedcba9876543211"
+                      pskd: "J01NME2"
+                      timeout: 333
+                      status: "pending"
+    post:
+      tags:
+        - Actions
+      summary: Add task(s) to the Actions collection.
+      description: |
+        Input to add one or more *Task* items to the *Actions* collection (i.e., enqueue).
+
+        ## Condition
+        - requires all items in the list to be valid *Task* items with all required attributes;
+          otherwise rejects whole list and returns 422 Conflict.
+        - requires the *Actions* collection to have free memory slots to enqueue the new items;
+          completed, stopped, or failed items in the collection may be removed (oldest first);
+          otherwise,
+            - if number of items send by client exceeds maximum number of items in collection, rejects whole list and returns 409 Conflict
+            - else if not enough items can be freed, rejects whole list and returns 503 Service Unavailable
+
+        ## On Success
+        - enqueues the tasks given in the `data` array
+        - each *Task* item is given a unique `id`
+        - each *Task* item is given a `status` attribute that is initialized with `pending`
+        - returns 200 OK listing all items enqueued with ID and status
+
+        ## On Failure
+        Returns one of the following:
+        - 409 Conflict, when the request contains more items than the maximum total number of items for the collection
+        - 415 Unsupported Media Type, when the request content type is not `application/vnd.api+json`, TODO: allow `application/json` or empty (tolerant server)
+        - 422 Unprocessable Content, when invalid items are included or required task-specific attributes are missing
+        - 503 Service Unavailable, when no more items can be enqueued (but the number of items in the request does not exceed the maximum)
+
+        ## General Background Logic (amended by task-specific background logic)
+        - when a *Task* item is executed, its `status` attribute changes to `active`
+        - when a *Task* item completes successfully, its `status` attribute changes to `completed`
+        - when a *Task* item completes unsuccessfully, its `status` attribute changes to `stopped`
+        - when a *Task* item fails, its `status` attribute changes to `failed`
+
+      parameters:
+        - name: Accept
+          description: Must be set to `application/vnd.api+json`
+          in: header
+          required: true
+          schema:
+            type: string
+            example: application/vnd.api+json
+      responses:
+        "200":
+          description: Task accepted and queue for execution.
+          content:
+            application/vnd.api+json:
+              schema:
+                type: object
+              example:
+                data:
+                  - id: 9ecae480-07a0-4b72-869d-15858196144f
+                    type: addThreadDeviceTask
+                    attributes:
+                      eui: "fedcba9876543210"
+                      pskd: "J01NME"
+                      timeout: 900
+                      status: "pending"
+        "400":
+          description: The client sent an invalid request. The client SHOULD perform action(s) to provide valid syntax before retrying the request.
+        "409":
+          description: Conflict parsing the task. The client SHOULD provide less tasks in the request.
+        "415":
+          description: Unsupported Media Type. The client SHOULD use a supported content type `application/vnd.api+json` or (TODO) `application/json`.
+        "422":
+          description: Unprocessable task. The client SHOULD perform action(s) to provide valid attributes or required task-specific attributes before retrying the request.
+        "503":
+          description: Service unavailable. Too many tasks pending. The client SHOULD retry later.
+      requestBody:
+        description: Creates a new task.
+        required: true
+        content:
+          application/vnd.api+json:
+            schema:
+              type: object
+              properties:
+                data:
+                  type: array
+                  items:
+                    type: object
+                    properties:
+                      type:
+                        type: string
+                        enum: [addThreadDeviceTask]
+                        description: Type of task
+                      attributes:
+                        type: object
+              required:
+                - data
+            examples:
+              addThreadDeviceTask:
+                summary: Add new Thread Device to the Network
+                description: |
+                  ### Background Logic
+                  - when the task status becomes `active`:
+                    - the *On-Mesh Commissioner* is started, if not already running
+                    - the given *EUI-64*, *Joining Device Credential (pskd)*, and timeout are added to the *Commissioner Joiner Table*
+                    - the task status is updated to `undiscovered`, before first attempts from *Joiner*, and `attempted` waiting for retries from *Joiner*
+                  - when the identified *Joiner* successfully joins the network, the task completes successfully by:
+                    - stopping the *On-Mesh Commissioner*, if it is the last active `addThreadDeviceTask`
+                    - setting the task status to `completed`
+                  - when the task times out without any *Joiner* attempts, the task status is set to `stopped`
+                  - when an error occurs, the task status is set to `failed`
+
+                value:
+                  data:
+                    - type: addThreadDeviceTask
+                      attributes:
+                        eui: "fedcba9876543210"
+                        pskd: "J01NME"
+                        timeout: 900
+
+    delete:
+      tags:
+        - Actions
+      summary: Remove all tasks from the queue of actions.
+      responses:
+        "204":
+          description: Tasks deleted.
+    options:
+      tags:
+        - Actions
+      summary: List of allowed operations.
+
+  /api/actions/{actionId}:
+    get:
+      tags:
+        - Actions
+      summary: Read Actions item
+      description: |
+        *Task* item in the *Actions* collection selected by its `id`.
+
+        ## Condition
+        Requires a *Task* item with the given `id` to exist;
+        otherwise returns 404 Not Found.
+      parameters:
+        - name: actionId
+          description: ID of the requested Action item (Task).
+          in: path
+          required: true
+          schema:
+            type: string
+            format: uuid
+        - name: Accept
+          description: Must be set to `application/vnd.api+json`
+          in: header
+          required: true
+          schema:
+            type: string
+            example: application/vnd.api+json
+
   /diagnostics:
     get:
       tags:
diff --git a/src/rest/resource.cpp b/src/rest/resource.cpp
index 7b89a10eba7..133a632173b 100644
--- a/src/rest/resource.cpp
+++ b/src/rest/resource.cpp
@@ -37,15 +37,10 @@
 
 #include "common/logging.hpp"
 #include "common/task_runner.hpp"
+#include "rest/extensions/rest_task_queue.hpp"
 #include "rest/resource.hpp"
 #include "utils/string_utils.hpp"
 
-extern "C" {
-#include <cJSON.h>
-extern task_node_t *task_queue;
-extern uint8_t      task_queue_len;
-}
-
 #define OT_PSKC_MAX_LENGTH 16
 #define OT_EXTENDED_PANID_LENGTH 8
 
@@ -76,6 +71,7 @@ extern uint8_t      task_queue_len;
 #define OT_REST_HTTP_STATUS_408 "408 Request Timeout"
 #define OT_REST_HTTP_STATUS_409 "409 Conflict"
 #define OT_REST_HTTP_STATUS_415 "415 Unsupported Media Type"
+#define OT_REST_HTTP_STATUS_422 "422 Unprocessable Content"
 #define OT_REST_HTTP_STATUS_500 "500 Internal Server Error"
 #define OT_REST_HTTP_STATUS_503 "503 Service Unavailable"
 
@@ -87,6 +83,12 @@ using std::chrono::steady_clock;
 using std::placeholders::_1;
 using std::placeholders::_2;
 
+extern "C" {
+#include <cJSON.h>
+extern task_node_t *task_queue;
+extern uint8_t      task_queue_len;
+}
+
 namespace otbr {
 namespace rest {
 
@@ -135,6 +137,9 @@ static std::string GetHttpStatus(HttpStatusCode aErrorCode)
     case HttpStatusCode::kStatusUnsupportedMediaType:
         httpStatus = OT_REST_HTTP_STATUS_415;
         break;
+    case HttpStatusCode::kStatusUnprocessable:
+        httpStatus = OT_REST_HTTP_STATUS_422;
+        break;
     case HttpStatusCode::kStatusInternalServerError:
         httpStatus = OT_REST_HTTP_STATUS_500;
         break;
@@ -1008,7 +1013,7 @@ void Resource::ApiActionPostHandler(const Request &aRequest, Response &aResponse
     std::string    responseMessage;
     std::string    errorCode;
     HttpStatusCode statusCode = HttpStatusCode::kStatusOk;
-    cJSON         *root;
+    cJSON         *root       = nullptr;
     cJSON         *dataArray;
     cJSON         *resp_data;
     cJSON         *datum;
@@ -1021,27 +1026,28 @@ void Resource::ApiActionPostHandler(const Request &aRequest, Response &aResponse
                  statusCode = HttpStatusCode::kStatusUnsupportedMediaType);
 
     root = cJSON_Parse(aRequest.GetBody().c_str());
-    VerifyOrExit(root != NULL, statusCode = HttpStatusCode::kStatusBadRequest);
+    VerifyOrExit(root != nullptr, statusCode = HttpStatusCode::kStatusBadRequest);
 
     // perform general validation before we attempt to
     // perform any task specific validation
     dataArray = cJSON_GetObjectItemCaseSensitive(root, "data");
-    VerifyOrExit((dataArray != NULL) && cJSON_IsArray(dataArray), statusCode = HttpStatusCode::kStatusConflict);
+    VerifyOrExit((dataArray != nullptr) && cJSON_IsArray(dataArray), statusCode = HttpStatusCode::kStatusUnprocessable);
 
     // validate the form and arguments of all tasks
     // before we attempt to perform processing on any of the tasks.
     for (int idx = 0; idx < cJSON_GetArraySize(dataArray); idx++)
     {
         // Require all items in the list to be valid Task items with all required attributes;
-        // otherwise rejects whole list and returns 409 Conflict.
+        // otherwise rejects whole list and returns 422 Unprocessable.
         // Unimplemented tasks counted as failed / invalid tasks
         VerifyOrExit(ACTIONS_TASK_VALID == validate_task(cJSON_GetArrayItem(dataArray, idx)),
-                     statusCode = HttpStatusCode::kStatusConflict);
+                     statusCode = HttpStatusCode::kStatusUnprocessable);
     }
 
     // Check queueing all tasks does not exceed the max number of tasks we can have queued
+    VerifyOrExit((TASK_QUEUE_MAX < cJSON_GetArraySize(dataArray)), statusCode = HttpStatusCode::kStatusConflict);
     VerifyOrExit((TASK_QUEUE_MAX - task_queue_len + can_remove_task_max()) > cJSON_GetArraySize(dataArray),
-                 statusCode = HttpStatusCode::kStatusConflict);
+                 statusCode = HttpStatusCode::kStatusServiceUnavailable);
 
     // Queue the tasks and prepare response data
     resp_data = cJSON_CreateArray();
@@ -1079,12 +1085,12 @@ void Resource::ApiActionPostHandler(const Request &aRequest, Response &aResponse
 
     // Clear the 'root' JSON object and release its memory (this should also delete 'data')
     cJSON_Delete(root);
-    root = NULL;
+    root = nullptr;
 
 exit:
     if (statusCode != HttpStatusCode::kStatusOk)
     {
-        if (root != NULL)
+        if (root != nullptr)
         {
             cJSON_Delete(root);
         }
@@ -1112,6 +1118,9 @@ void Resource::ApiActionGetHandler(const Request &aRequest, Response &aResponse)
     // and another attempt after 2s
     ApiActionRepeatedTaskRunner(2000);
 
+    resp      = cJSON_CreateObject();
+    task_node = task_queue;
+
     if (aRequest.GetHeaderValue(OT_REST_ACCEPT_HEADER).compare(OT_REST_CONTENT_TYPE_JSONAPI) == 0)
     {
         aResponse.SetContentType(OT_REST_CONTENT_TYPE_JSONAPI);
@@ -1119,7 +1128,6 @@ void Resource::ApiActionGetHandler(const Request &aRequest, Response &aResponse)
         if (!itemId.empty())
         {
             // return the item
-            task_node = task_queue;
             while (std::string(task_node->id_str) != itemId)
             {
                 VerifyOrExit(task_node->next != nullptr, statusCode = HttpStatusCode::kStatusResourceNotFound);
@@ -1128,18 +1136,14 @@ void Resource::ApiActionGetHandler(const Request &aRequest, Response &aResponse)
             }
             evaluate_task(task_node);
 
-            resp = cJSON_CreateObject();
             cJSON_AddItemToObject(resp, "data", task_to_json(task_node));
             resp_body = std::string(cJSON_PrintUnformatted(resp));
         }
         else
         {
             // return all items
-            task_node = task_queue;
-            resp      = cJSON_CreateObject();
-
             resp_data = cJSON_CreateArray();
-            while (task_node != NULL)
+            while (task_node != nullptr)
             {
                 evaluate_task(task_node);
                 cJSON_AddItemToObject(resp_data, "data", task_to_json(task_node));
diff --git a/src/rest/rest_web_server.cpp b/src/rest/rest_web_server.cpp
index 92aad2d6581..e23d6ece97d 100644
--- a/src/rest/rest_web_server.cpp
+++ b/src/rest/rest_web_server.cpp
@@ -81,13 +81,6 @@ void RestWebServer::Init(void)
     mInstance         = threadHelper->GetInstance();
     if (mInstance != NULL)
     {
-        // Initialize the mutex and creates a thread to process the 'api/actions'
-        // Pass the openthread instance that can be used to call openthread apis.
-
-        // removed 'task' (pthread) in the sense of a task for multithreading and do not create such
-        // parallel task objects that consequently require complicated lock and semaphore mechanisms.
-        // TODO: stick with term 'action' for an activity that requires indirect response.
-
         // Initialize the instance pointer
         rest_task_queue_task_init(mInstance);
     }
diff --git a/src/rest/types.hpp b/src/rest/types.hpp
index fb74dca86ce..b4e51d83f06 100644
--- a/src/rest/types.hpp
+++ b/src/rest/types.hpp
@@ -79,6 +79,7 @@ enum class HttpStatusCode : std::uint16_t
     kStatusRequestTimeout       = 408,
     kStatusConflict             = 409,
     kStatusUnsupportedMediaType = 415,
+    kStatusUnprocessable        = 422,
     kStatusInternalServerError  = 500,
     kStatusServiceUnavailable   = 503,
 };
diff --git a/tests/restjsonapi/install_bruno_cli b/tests/restjsonapi/install_bruno_cli
index 96cbfdb3c10..a8ef2e23891 100755
--- a/tests/restjsonapi/install_bruno_cli
+++ b/tests/restjsonapi/install_bruno_cli
@@ -31,8 +31,9 @@
 
 # installs fnm (Fast Node Manager)
 curl -fsSL https://fnm.vercel.app/install | bash
-# activate fnm
+# shellcheck source=/dev/null
 source ~/.bashrc
+# activate fnm
 # download and install Node.js
 fnm use --install-if-missing 20
 # verifies the right Node.js version is in the environment