diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4b87969f0..fc8d81f6f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -33,6 +33,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - Added response schema for `PUT` and `DELETE /_plugins/_transform/{id}` ([#722](https://github.com/opensearch-project/opensearch-api-specification/pull/716))
 - Added response schema for `GET /_plugins/_knn/warmup/{index}` ([#717](https://github.com/opensearch-project/opensearch-api-specification/pull/717))
 - Added support for multiple test verbs ([#724](https://github.com/opensearch-project/opensearch-api-specification/pull/724))
+- Added support for combining output variables ([#737](https://github.com/opensearch-project/opensearch-api-specification/pull/737))
 
 ### 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))
diff --git a/TESTING_GUIDE.md b/TESTING_GUIDE.md
index 362f6359f..52b584982 100644
--- a/TESTING_GUIDE.md
+++ b/TESTING_GUIDE.md
@@ -230,7 +230,9 @@ Consider the following chapters in [ml/model_groups](tests/plugins/ml/ml/model_g
 ```
 As you can see, the `output` field in the first chapter saves the `model_group_id` from the response body. This value is then used in the subsequent chapters to query and delete the model group.
 
-You can also supply defaults for output values, e.g. for `payload._version` used in [cluster/routing/awareness/weights.yaml](tests/routing/cluster/routing/awareness/weights.yaml).
+You can combine multiple values, e.g. `task_id: ${task.node}:${task.id}`.
+
+You can supply defaults for output values, e.g. for `payload._version` used in [cluster/routing/awareness/weights.yaml](tests/routing/cluster/routing/awareness/weights.yaml).
 
 ```
 version:
diff --git a/tests/default/tasks/list.yaml b/tests/default/_core/tasks.yaml
similarity index 50%
rename from tests/default/tasks/list.yaml
rename to tests/default/_core/tasks.yaml
index a687e170c..d9ce9a2e1 100644
--- a/tests/default/tasks/list.yaml
+++ b/tests/default/_core/tasks.yaml
@@ -1,25 +1,35 @@
 $schema: ../../../json_schemas/test_story.schema.yaml
 
-description: Test tasks list endpoint.
+description: Test tasks endpoint.
 chapters:
   - synopsis: List tasks grouped by node.
     path: /_tasks
     method: GET
     parameters:
       group_by: nodes
-    response:
-      status: 200
   - synopsis: List tasks grouped by parent.
     path: /_tasks
     method: GET
     parameters:
       group_by: parents
-    response:
-      status: 200
   - synopsis: List tasks grouped by none.
+    id: task
     path: /_tasks
     method: GET
     parameters:
       group_by: none
-    response:
-      status: 200
\ No newline at end of file
+    output:
+      id: payload.tasks[0].id
+      node: payload.tasks[0].node
+  # - synopsis: Get task by id.
+  #   id: task
+  #   path: /_tasks/{task_id}
+  #   method: GET
+  #   parameters:
+  #     task_id: ${task.node}:${task.id}
+  #   response:
+  #     status: 200
+  #     payload:
+  #       task:
+  #         node: ${task.node}
+  #         id: ${task.id}
diff --git a/tests/default/_core/tasks/cancel.yaml b/tests/default/_core/tasks/cancel.yaml
new file mode 100644
index 000000000..fe467270b
--- /dev/null
+++ b/tests/default/_core/tasks/cancel.yaml
@@ -0,0 +1,7 @@
+$schema: ../../../../json_schemas/test_story.schema.yaml
+
+description: Test tasks endpoint.
+chapters:
+  - synopsis: Cancel all tasks.
+    path: /_tasks/_cancel
+    method: POST
diff --git a/tools/src/tester/StoryEvaluator.ts b/tools/src/tester/StoryEvaluator.ts
index a17df942f..839760dc3 100644
--- a/tools/src/tester/StoryEvaluator.ts
+++ b/tools/src/tester/StoryEvaluator.ts
@@ -217,10 +217,7 @@ export default class StoryEvaluator {
   static #extract_params_variables(parameters: Record<string, Parameter>, variables: Set<OutputReference>): void {
     Object.values(parameters ?? {}).forEach((param) => {
       if (typeof param === 'string') {
-        const ref = OutputReference.parse(param)
-        if (ref) {
-          variables.add(ref)
-        }
+        OutputReference.parse(param).forEach((ref) => variables.add(ref))
       }
     })
   }
@@ -229,10 +226,7 @@ export default class StoryEvaluator {
     const request_type = typeof request
     switch (request_type) {
       case 'string': {
-        const ref = OutputReference.parse(request as string)
-        if (ref !== undefined) {
-          variables.add(ref)
-        }
+        OutputReference.parse(request as string).forEach((ref) => variables.add(ref))
         break
       }
       case 'object': {
diff --git a/tools/src/tester/StoryOutputs.ts b/tools/src/tester/StoryOutputs.ts
index 41b8d9e71..838d66763 100644
--- a/tools/src/tester/StoryOutputs.ts
+++ b/tools/src/tester/StoryOutputs.ts
@@ -48,12 +48,13 @@ export class StoryOutputs {
   }
 
   resolve_string (str: string): any {
-    const ref = OutputReference.parse(str)
-    if (ref) {
-      return this.get_output_value(ref.chapter_id, ref.output_name)
-    } else {
-      return str
-    }
+    return OutputReference.replace(str, (chapter_id, output_name) => {
+      if (chapter_id === undefined || output_name === undefined) {
+        throw new Error(`Invalid output references in ${str}.`)
+      }
+
+      return this.get_output_value(chapter_id as string, output_name as string)
+    })
   }
 
   resolve_value (payload: any): any {
diff --git a/tools/src/tester/types/eval.types.ts b/tools/src/tester/types/eval.types.ts
index e65b80c3c..f29714afe 100644
--- a/tools/src/tester/types/eval.types.ts
+++ b/tools/src/tester/types/eval.types.ts
@@ -87,16 +87,42 @@ export enum Result {
 export class OutputReference {
   chapter_id: string
   output_name: string
-  private constructor (chapter_id: string, output_name: string) {
+
+  private constructor(chapter_id: string, output_name: string) {
     this.chapter_id = chapter_id
     this.output_name = output_name
   }
 
-  static parse (str: string): OutputReference | undefined {
-    if (str.startsWith('${') && str.endsWith('}')) {
-      const spl = str.slice(2, -1).split('.', 2)
-      return { chapter_id: spl[0], output_name: spl[1] }
+  static parse(str: string): OutputReference[] {
+    const pattern = /\$\{([^}]+)\}/g
+    let match
+    var result = []
+    while ((match = pattern.exec(str)) !== null) {
+      const spl = this.#split(match[1], '.', 2)
+      result.push(new OutputReference(spl[0], spl[1]))
     }
-    return undefined
+    return result
+  }
+
+  static replace(str: string, callback: (chapter_id: any, variable: any) => string): any {
+    // preserve type if 1 value is returned
+    let full_match = str.match(/^\$\{([^}]+)\}$/)
+    if (full_match) {
+      const spl = this.#split(full_match[1], '.', 2)
+      return callback(spl[0], spl[1])
+    } else return str.replace(/\$\{([^}]+)\}/g, (_, k) => {
+      const spl = this.#split(k, '.', 2)
+      return callback(spl[0], spl[1])
+    });
+  }
+
+  static #split(str: any, delim: string, count: number): string[] {
+    if (str === undefined) return [str]
+    if (count <= 0) return [str]
+    const parts = str.split(delim)
+    if (parts.length <= count) return parts
+    const result = parts.slice(0, count - 1)
+    result.push(parts.slice(count - 1).join(delim))
+    return result
   }
 }
diff --git a/tools/tests/tester/StoryOutputs.test.ts b/tools/tests/tester/StoryOutputs.test.ts
index 3017b7a66..044531328 100644
--- a/tools/tests/tester/StoryOutputs.test.ts
+++ b/tools/tests/tester/StoryOutputs.test.ts
@@ -55,13 +55,19 @@ test('resolve_params', () => {
     a: '${chapter_id.x}',
     b: '${chapter_id.y}',
     c: 3,
-    d: 'str'
+    d: 'str',
+    e: '${chapter_id.x}:${chapter_id.y}',
+    f: 'x=${chapter_id.x}',
+    g: '${chapter_id.y}=y'
   }
   expect(story_outputs.resolve_params(parameters)).toEqual({
     a: 1,
     b: 2,
     c: 3,
-    d: 'str'
+    d: 'str',
+    e: '1:2',
+    f: 'x=1',
+    g: '2=y'
   })
 })
 
diff --git a/tools/tests/types/eval.types.test.ts b/tools/tests/types/eval.types.test.ts
new file mode 100644
index 000000000..76f7f3ac2
--- /dev/null
+++ b/tools/tests/types/eval.types.test.ts
@@ -0,0 +1,23 @@
+/*
+* Copyright OpenSearch Contributors
+* SPDX-License-Identifier: Apache-2.0
+*
+* The OpenSearch Contributors require contributions made to
+* this file be licensed under the Apache-2.0 license or a
+* compatible open source license.
+*/
+
+import { OutputReference } from "tester/types/eval.types";
+
+describe('OutputReference', () => {
+  let f = (id: any, k: any): string => `[${id}:${k}]`
+
+  describe('replace', () => {
+    it('replaces', () => {
+      expect(OutputReference.replace('string', f)).toEqual('string')
+      expect(OutputReference.replace('${k.v}', f)).toEqual('[k:v]')
+      expect(OutputReference.replace('${k.value}', f)).toEqual('[k:value]')
+      expect(OutputReference.replace('${k.v.m}', f)).toEqual('[k:v.m]')
+    })
+  })
+});