diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5854a451c..350c17fe3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - Added `/_cluster/stats/{metric}/nodes/{node_id}` and `/_cluster/stats/{metric}/{index_metric}/nodes/{node_id}` ([#639](https://github.com/opensearch-project/opensearch-api-specification/pull/639))
 - Added `PhoneAnalyzer` from `analysis-phonenumber` plugin ([#609](https://github.com/opensearch-project/opensearch-api-specification/pull/609))
 - Added `/_list/indices` & `/_list/shards` api specs ([#613](https://github.com/opensearch-project/opensearch-api-specification/pull/613))
+- Added `GET` and `HEAD /{index}/_source/{id}` returning `404` ([#673](https://github.com/opensearch-project/opensearch-api-specification/pull/673))
 
 ### Removed
 - Removed unsupported `_common.mapping:SourceField`'s `mode` field and associated `_common.mapping:SourceFieldMode` enum ([#652](https://github.com/opensearch-project/opensearch-api-specification/pull/652))
@@ -33,6 +34,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - Added schema for security API error responses ([#646](https://github.com/opensearch-project/opensearch-api-specification/pull/646))
 - Fixed `/{index}/_create/{id}` returning `201` ([#669](https://github.com/opensearch-project/opensearch-api-specification/pull/669))
 - Fixed `ml._common.yaml#SearchModelsResponse` and `SearchModelsHitsHit` ([#672](https://github.com/opensearch-project/opensearch-api-specification/pull/672))
+- Fixed `refresh` options to allow `boolean` and `string` ([#673](https://github.com/opensearch-project/opensearch-api-specification/pull/673))
 
 ## [0.1.0] - 2024-10-25
 
diff --git a/spec/namespaces/_core.yaml b/spec/namespaces/_core.yaml
index 0b9a6f138..bd5afec8c 100644
--- a/spec/namespaces/_core.yaml
+++ b/spec/namespaces/_core.yaml
@@ -2047,6 +2047,8 @@ paths:
       responses:
         '200':
           $ref: '#/components/responses/get_source@200'
+        '404':
+          $ref: '#/components/responses/get_source@404'
     head:
       operationId: exists_source.0
       x-operation-group: exists_source
@@ -2069,6 +2071,8 @@ paths:
       responses:
         '200':
           $ref: '#/components/responses/exists_source@200'
+        '404':
+          $ref: '#/components/responses/exists_source@404'
   /{index}/_termvectors:
     get:
       operationId: termvectors.0
@@ -2913,6 +2917,9 @@ components:
     exists_source@200:
       content:
         application/json: {}
+    exists_source@404:
+      content:
+        application/json: {}
     explain@200:
       content:
         application/json:
@@ -3019,6 +3026,11 @@ components:
         application/json:
           schema:
             type: object
+    get_source@404:
+      content:
+        application/json:
+          schema:
+            $ref: '../schemas/query._common.yaml#/components/schemas/ErrorResponse'
     index@200:
       content:
         application/json:
@@ -4000,7 +4012,7 @@ components:
       name: refresh
       description: If `true`, OpenSearch refreshes all shards involved in the delete by query after the request completes.
       schema:
-        type: boolean
+        $ref: '../schemas/_common.yaml#/components/schemas/Refresh'
       style: form
     delete_by_query::query.request_cache:
       in: query
@@ -4256,7 +4268,7 @@ components:
       name: refresh
       description: If `true`, OpenSearch refreshes all shards involved in the delete by query after the request completes.
       schema:
-        type: boolean
+        $ref: '../schemas/_common.yaml#/components/schemas/Refresh'
       style: form
     exists::query.routing:
       in: query
@@ -4352,7 +4364,7 @@ components:
       name: refresh
       description: If `true`, OpenSearch refreshes all shards involved in the delete by query after the request completes.
       schema:
-        type: boolean
+        $ref: '../schemas/_common.yaml#/components/schemas/Refresh'
       style: form
     exists_source::query.routing:
       in: query
@@ -4590,7 +4602,7 @@ components:
       name: refresh
       description: If true, OpenSearch refreshes the affected shards to make this operation visible to search. If false, do nothing with refreshes.
       schema:
-        type: boolean
+        $ref: '../schemas/_common.yaml#/components/schemas/Refresh'
       style: form
     get::query.routing:
       in: query
@@ -4705,7 +4717,7 @@ components:
       name: refresh
       description: If true, OpenSearch refreshes the affected shards to make this operation visible to search. If false, do nothing with refreshes.
       schema:
-        type: boolean
+        $ref: '../schemas/_common.yaml#/components/schemas/Refresh'
       style: form
     get_source::query.routing:
       in: query
@@ -4893,7 +4905,7 @@ components:
       name: refresh
       description: If `true`, the request refreshes relevant shards before retrieving documents.
       schema:
-        type: boolean
+        $ref: '../schemas/_common.yaml#/components/schemas/Refresh'
       style: form
     mget::query.routing:
       in: query
@@ -5237,7 +5249,7 @@ components:
       name: refresh
       description: If `true`, the request refreshes affected shards to make this operation visible to search.
       schema:
-        type: boolean
+        $ref: '../schemas/_common.yaml#/components/schemas/Refresh'
       style: form
     reindex::query.requests_per_second:
       in: query
@@ -6357,7 +6369,7 @@ components:
       name: refresh
       description: If `true`, OpenSearch refreshes affected shards to make the operation visible to search.
       schema:
-        type: boolean
+        $ref: '../schemas/_common.yaml#/components/schemas/Refresh'
       style: form
     update_by_query::query.request_cache:
       in: query
diff --git a/spec/schemas/_common.yaml b/spec/schemas/_common.yaml
index 5ef209d8a..229bdc970 100644
--- a/spec/schemas/_common.yaml
+++ b/spec/schemas/_common.yaml
@@ -767,11 +767,13 @@ components:
     NodeName:
       type: string
     Refresh:
-      type: string
-      enum:
-        - 'false'
-        - 'true'
-        - wait_for
+      oneOf:
+        - type: boolean
+        - type: string
+          enum:
+            - 'false'
+            - 'true'
+            - wait_for
     WaitForActiveShards:
       oneOf:
         - title: count
diff --git a/tests/default/_core/msearch.yaml b/tests/default/_core/msearch.yaml
index 79d92c9b8..6cff72802 100644
--- a/tests/default/_core/msearch.yaml
+++ b/tests/default/_core/msearch.yaml
@@ -23,7 +23,7 @@ prologues:
         - {create: {_index: movies, _id: movie2}}
         - {director: Nicolas Winding Refn, title: Drive, year: 1960}
 chapters:
-  - synopsis: Run multiple search requests in single request.
+  - synopsis: Run multiple search requests in single request (GET).
     path: /_msearch
     method: GET
     request:
@@ -53,3 +53,33 @@ chapters:
                   _id: movie1
                 - _index: movies
                   _id: movie2
+  - synopsis: Run multiple search requests in single request (POST).
+    path: /_msearch
+    method: POST
+    request:
+      content_type: application/x-ndjson
+      payload:
+        - {index: movies}
+        - {query: {match_all: {}}}
+        - {index: books}
+        - {query: {match_all: {}}}
+    response:
+      status: 200
+      payload:
+        responses:
+          - hits:
+              total:
+                value: 2
+                relation: eq
+              hits:
+                - _index: movies
+                  _id: movie1
+                - _index: movies
+                  _id: movie2
+          - hits:
+              total:
+                value: 1
+                relation: eq
+              hits:
+                - _index: books
+                  _id: book1
diff --git a/tests/default/indices/mget.yaml b/tests/default/indices/mget.yaml
index 9b81f3dd8..07732a33c 100644
--- a/tests/default/indices/mget.yaml
+++ b/tests/default/indices/mget.yaml
@@ -18,7 +18,7 @@ prologues:
         - {create: {_index: movies, _id: movie2}}
         - {director: Nicolas Winding Refn, title: Drive, year: 1960}
 chapters:
-  - synopsis: Retrieve documents from multiple indexes.
+  - synopsis: Retrieve documents from multiple indexes (GET).
     path: /{index}/_mget
     method: GET
     parameters:
@@ -46,3 +46,21 @@ chapters:
             _id: movie1
           - _index: movies
             _id: movie2
+  - synopsis: Retrieve documents from multiple indexes (POST).
+    path: /{index}/_mget
+    method: POST
+    parameters:
+      index: movies
+    request:
+      payload:
+        docs:
+          - _id: movie1
+          - _id: movie2
+    response:
+      status: 200
+      payload:
+        docs:
+          - _index: movies
+            _id: movie1
+          - _index: movies
+            _id: movie2
diff --git a/tests/default/indices/refresh.yaml b/tests/default/indices/refresh.yaml
index eb8f69057..a17644e53 100644
--- a/tests/default/indices/refresh.yaml
+++ b/tests/default/indices/refresh.yaml
@@ -14,7 +14,17 @@ prologues:
         year: 1991
     status: [201]
 chapters:
-  - synopsis: Refresh an index.
+  - synopsis: Refresh an index (GET).
+    path: /{index}/_refresh
+    method: GET
+    parameters:
+      index: movies
+    response:
+      status: 200
+      payload:
+        _shards:
+          failed: 0
+  - synopsis: Refresh an index (POST).
     path: /{index}/_refresh
     method: POST
     parameters:
diff --git a/tests/default/indices/source.yaml b/tests/default/indices/source.yaml
new file mode 100644
index 000000000..4d7c234c2
--- /dev/null
+++ b/tests/default/indices/source.yaml
@@ -0,0 +1,52 @@
+$schema: ../../../json_schemas/test_story.schema.yaml
+
+description: Test retrieving a document source.
+epilogues:
+  - path: /movies
+    method: DELETE
+    status: [200, 404]
+prologues:
+  - path: /movies/_doc/1
+    method: POST
+    parameters:
+      refresh: true
+    request:
+      payload:
+        title: Beauty and the Beast
+        year: 1991
+chapters:
+  - synopsis: Retrieve the document source.
+    path: /{index}/_source/{id}
+    method: GET
+    parameters:
+      index: movies
+      id: '1'
+    response:
+      status: 200
+      payload:
+        title: Beauty and the Beast
+        year: 1991
+  - synopsis: Retrieve a non-existent document source.
+    path: /{index}/_source/{id}
+    method: GET
+    parameters:
+      index: movies
+      id: '2'
+    response:
+      status: 404
+  - synopsis: Check whether the document exists.
+    path: /{index}/_source/{id}
+    method: HEAD
+    parameters:
+      index: movies
+      id: '1'
+    response:
+      status: 200
+  - synopsis: Check whether the document exists.
+    path: /{index}/_source/{id}
+    method: HEAD
+    parameters:
+      index: movies
+      id: '2'
+    response:
+      status: 404
diff --git a/tests/default/indices/update.yaml b/tests/default/indices/update.yaml
new file mode 100644
index 000000000..bbe553fd7
--- /dev/null
+++ b/tests/default/indices/update.yaml
@@ -0,0 +1,82 @@
+$schema: ../../../json_schemas/test_story.schema.yaml
+
+description: Test updating a document.
+epilogues:
+  - path: /movies
+    method: DELETE
+    status: [200, 404]
+prologues:
+  - path: /movies/_doc/1
+    method: POST
+    parameters:
+      refresh: true
+    request:
+      payload:
+        title: Beauty and the Beast
+        year: 1990
+chapters:
+  - synopsis: Update a document in the index.
+    path: /{index}/_update/{id}
+    method: POST
+    parameters:
+      index: movies
+      id: '1'
+      refresh: true
+    request:
+      payload:
+        doc:
+          title: Beauty and the Beast
+          year: 1991
+    response:
+      status: 200
+      payload:
+        result: updated
+  - synopsis: Update a document in the index using a script.
+    path: /{index}/_update/{id}
+    method: POST
+    parameters:
+      index: movies
+      id: '1'
+    request:
+      payload:
+        script:
+          source: ctx._source.year += params.value
+          lang: painless
+          params:
+            value: 10
+    response:
+      status: 200
+      payload:
+        result: updated
+  - synopsis: Upsert a document.
+    path: /{index}/_update/{id}
+    method: POST
+    parameters:
+      index: movies
+      id: '1'
+    request:
+      payload:
+        doc:
+          title: Drive
+        upsert:
+          title: Drive
+    response:
+      status: 200
+      payload:
+        result: updated
+  - synopsis: Upsert a document (doc_as_upsert).
+    path: /{index}/_update/{id}
+    method: POST
+    parameters:
+      index: movies
+      id: '1'
+    request:
+      payload:
+        doc:
+          title: Drive
+          year: 2011
+        doc_as_upsert: true
+    response:
+      status: 200
+      payload:
+        result: updated
diff --git a/tests/plugins/streaming/_core/bulk/stream.yaml b/tests/plugins/streaming/_core/bulk/stream.yaml
index 7560ea715..a35c98f05 100644
--- a/tests/plugins/streaming/_core/bulk/stream.yaml
+++ b/tests/plugins/streaming/_core/bulk/stream.yaml
@@ -15,6 +15,15 @@ chapters:
       payload:
         - {create: {_index: movies}}
         - {director: Bennett Miller, title: Moneyball, year: 2011}
+  - synopsis: Update an index.
+    version: '>= 2.17'
+    path: /_bulk/stream
+    method: PUT
+    request:
+      content_type: application/x-ndjson
+      payload:
+        - {create: {_index: movies}}
+        - {director: Bennett Miller, title: Drive, year: 2011}
   - synopsis: Delete document in an index.
     version: '2.17'
     path: /_bulk/stream