diff --git a/CHANGELOG.md b/CHANGELOG.md
index 63d8ffb13..ab8da74ca 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -61,7 +61,8 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - Fixed `text/plain` response in `/_cat` ([#357](https://github.com/opensearch-project/opensearch-api-specification/pull/357))
 - Fixed `/_cat/cluster_manager`, `/_cat/allocation`, `/_cat/shards`, and `/_cat/thread_pool` ([#373](https://github.com/opensearch-project/opensearch-api-specification/pull/373))
 - Fixed optional field in `/_nodes` ([#365](https://github.com/opensearch-project/opensearch-api-specification/pull/365))
-
+- Fixed `/{index}/_open` can return a `task` ([#376](https://github.com/opensearch-project/opensearch-api-specification/pull/376))
+ 
 ### Security
 
 [Unreleased]: https://github.com/opensearch-project/opensearch-api-specification/commits/main/
diff --git a/SPECIFICATION_TESTING.md b/SPECIFICATION_TESTING.md
index 15afa704b..b40283e4c 100644
--- a/SPECIFICATION_TESTING.md
+++ b/SPECIFICATION_TESTING.md
@@ -40,7 +40,7 @@ Note: Remember to set the `OPENSEARCH_PASSWORD` environment variable everytime y
 
 ## Writing Spec Tests
 
-The spec tests reside in the [tests/](tests) directory. Tests are organized in folders that match [namespaces](spec/namespaces). For example, tests for APIs defined in [spec/namespaces/indices.yaml](spec/namespaces/indices.yaml) can be found in [tests/indices/index.yaml](tests/indices/index.yaml) (for `/{index}`), and [tests/indices/_doc.yaml](tests/indices/_doc.yaml) (for `/{index}/_doc`).
+The spec tests reside in the [tests/](tests) directory. Tests are organized in folders that match [namespaces](spec/namespaces). For example, tests for APIs defined in [spec/namespaces/indices.yaml](spec/namespaces/indices.yaml) can be found in [tests/indices/index.yaml](tests/indices/index.yaml) (for `/{index}`), and [tests/indices/doc.yaml](tests/indices/doc.yaml) (for `/{index}/_doc`).
 
 Each yaml file in the tests directory represents a test story that tests a collection of related operations.
 
diff --git a/spec/namespaces/indices.yaml b/spec/namespaces/indices.yaml
index 9c524871c..2bda325dc 100644
--- a/spec/namespaces/indices.yaml
+++ b/spec/namespaces/indices.yaml
@@ -2393,15 +2393,22 @@ components:
       content:
         application/json:
           schema:
-            type: object
-            properties:
-              acknowledged:
-                type: boolean
-              shards_acknowledged:
-                type: boolean
-            required:
-              - acknowledged
-              - shards_acknowledged
+            oneOf:
+              - type: object
+                properties:
+                  task:
+                    $ref: '../schemas/_common.yaml#/components/schemas/TaskId'
+                additionalProperties: false
+              - type: object
+                properties:
+                  acknowledged:
+                    type: boolean
+                  shards_acknowledged:
+                    type: boolean
+                required:
+                  - acknowledged
+                  - shards_acknowledged
+                additionalProperties: false
     indices.put_alias@200:
       description: ''
       content:
diff --git a/spec/schemas/nodes.info.yaml b/spec/schemas/nodes.info.yaml
index f687b4523..30f1103d7 100644
--- a/spec/schemas/nodes.info.yaml
+++ b/spec/schemas/nodes.info.yaml
@@ -32,7 +32,7 @@ components:
               additionalProperties:
                 $ref: '#/components/schemas/NodeInfo'
             _nodes:
-                $ref: 'nodes._common.yaml#/components/schemas/NodesResponseBase'
+              $ref: 'nodes._common.yaml#/components/schemas/NodesResponseBase'
           required:
             - cluster_name
             - nodes
@@ -101,7 +101,7 @@ components:
           additionalProperties:
             $ref: '#/components/schemas/NodeInfoAggregation'
         search_pipelines:
-            $ref: '#/components/schemas/NodeInfoSearchPipelines'
+          $ref: '#/components/schemas/NodeInfoSearchPipelines'
       required:
         - attributes
         - build_hash
diff --git a/tests/indices/close.yaml b/tests/indices/close.yaml
new file mode 100644
index 000000000..0766f3085
--- /dev/null
+++ b/tests/indices/close.yaml
@@ -0,0 +1,38 @@
+$schema: ../../json_schemas/test_story.schema.yaml
+
+description: Test closing an index.
+prologues:
+  - path: /movies
+    method: PUT
+    status: [200]
+epilogues:
+  - path: /movies
+    method: DELETE
+    status: [200, 404]
+chapters:
+  - synopsis: Close an index.
+    path: /{index}/_close
+    method: POST
+    parameters:
+      index: movies
+      allow_no_indices: true
+      expand_wildcards: all
+      ignore_unavailable: true
+      wait_for_active_shards: 0
+      cluster_manager_timeout: 30s
+      timeout: 30s
+    response:
+      status: 200
+      payload:
+        indices:
+          movies:
+            closed: true
+  - synopsis: Close an already closed index.
+    path: /{index}/_close
+    method: POST
+    parameters:
+      index: movies
+    response:
+      status: 200
+      payload:
+        indices: {}
diff --git a/tests/indices/_doc.yaml b/tests/indices/doc.yaml
similarity index 100%
rename from tests/indices/_doc.yaml
rename to tests/indices/doc.yaml
diff --git a/tests/indices/open.yaml b/tests/indices/open.yaml
new file mode 100644
index 000000000..dbcade065
--- /dev/null
+++ b/tests/indices/open.yaml
@@ -0,0 +1,63 @@
+$schema: ../../json_schemas/test_story.schema.yaml
+
+description: Test opening an index.
+prologues:
+  - path: /movies
+    method: PUT
+    status: [200]
+  - path: /games
+    method: PUT
+    status: [200]
+  - path: /movies/_close
+    method: POST
+    status: [200]
+  - path: /games/_close
+    method: POST
+    status: [200]
+epilogues:
+  - path: /movies,games
+    method: DELETE
+    status: [200, 404]
+chapters:
+  - synopsis: Open a closed index.
+    path: /{index}/_open
+    method: POST
+    parameters:
+      index: movies
+      allow_no_indices: true
+      expand_wildcards: all
+      ignore_unavailable: true
+      wait_for_active_shards: 0
+      cluster_manager_timeout: 30s
+      timeout: 30s
+      wait_for_completion: true
+    response:
+      status: 200
+      payload:
+        shards_acknowledged: true
+        acknowledged: true
+  - synopsis: Open a closed index (wait_for_completion=false).
+    path: /{index}/_open
+    method: POST
+    parameters:
+      index: movies
+      allow_no_indices: true
+      expand_wildcards: all
+      ignore_unavailable: true
+      wait_for_active_shards: 0
+      cluster_manager_timeout: 30s
+      timeout: 30s
+      wait_for_completion: false
+      task_execution_timeout: 1m
+    response:
+      status: 200
+  - synopsis: Open an already opened index.
+    path: /{index}/_open
+    method: POST
+    parameters:
+      index: movies
+    response:
+      status: 200
+      payload:
+        shards_acknowledged: true
+        acknowledged: true
diff --git a/tools/src/tester/ChapterReader.ts b/tools/src/tester/ChapterReader.ts
index 7cb5219e7..02e534552 100644
--- a/tools/src/tester/ChapterReader.ts
+++ b/tools/src/tester/ChapterReader.ts
@@ -61,7 +61,7 @@ export default class ChapterReader {
       response.message = payload.error?.reason ?? e.response.statusText
       response.error = e
 
-      this.logger.info(`<= ${response.status} (${response.content_type}) | ${response.payload ?? response.message}`)
+      this.logger.info(`<= ${response.status} (${response.content_type}) | ${response.payload !== undefined ? to_json(response.payload) : response.message}`)
     })
     return response as ActualResponse
   }