diff --git a/docker-compose.yaml b/docker-compose.yaml
index 42b73ff96..ed8369286 100644
--- a/docker-compose.yaml
+++ b/docker-compose.yaml
@@ -13,7 +13,7 @@ services:
     build:
       context: .
       dockerfile: ./gateway/Dockerfile-gateway
-    image: ghcr.io/biosimulators/bio-compose-server-gateway:0.0.5-dev
+    image: ghcr.io/biosimulators/bio-compose-server-gateway:0.0.6-dev
     container_name: gateway
     networks:
       - compnet
diff --git a/gateway/main.py b/gateway/main.py
index 3cb9f6c91..8292a3598 100644
--- a/gateway/main.py
+++ b/gateway/main.py
@@ -1,15 +1,13 @@
-import dataclasses
 import json
 import os
 import uuid
-from typing import *
-
 import dotenv
-from tempfile import mkdtemp
+from typing import *
+# from tempfile import mkdtemp
 
 import uvicorn
 from fastapi import FastAPI, File, UploadFile, HTTPException, Query, APIRouter, Body
-from fastapi.responses import FileResponse
+# from fastapi.responses import FileResponse
 from pydantic import BeforeValidator
 from starlette.middleware.cors import CORSMiddleware
 
@@ -19,21 +17,28 @@
     # ReaddyParticleConfig,
     # ReaddyRun,
     # SmoldynRun,
-    DbClientResponse,
     # AgentParameters,
-    BigraphRegistryAddresses,
     # IncompleteJob,
     # JobStatus,
+    BigraphRegistryAddresses,
+    DbClientResponse,
     CompositionNode,
     CompositionSpec,
     CompositionRun,
-    OutputData
+    OutputData,
+    ValidatedComposition
 )
 from shared.database import MongoConnector
-# from shared.io import write_uploaded_file, download_file_from_bucket
 from shared.log_config import setup_logging
 from shared.utils import get_project_version
-from shared.environment import ENV_PATH, DEFAULT_DB_NAME, DEFAULT_DB_TYPE, DEFAULT_JOB_COLLECTION_NAME, DEFAULT_BUCKET_NAME
+from shared.environment import (
+    ENV_PATH,
+    DEFAULT_DB_NAME,
+    DEFAULT_DB_TYPE,
+    DEFAULT_JOB_COLLECTION_NAME,
+    DEFAULT_BUCKET_NAME
+)
+# from shared.io import write_uploaded_file, download_file_from_bucket
 
 
 logger = setup_logging(__file__)
@@ -148,7 +153,7 @@ async def get_process_bigraph_addresses() -> BigraphRegistryAddresses:
 
 @app.post(
     "/validate-composition",
-    # response_model=CompositionRun,
+    response_model=ValidatedComposition,
     tags=["Composition"],
     operation_id="validate-composition",
     summary="Validate Simulation Experiment Design specification file.",
@@ -156,8 +161,7 @@ async def get_process_bigraph_addresses() -> BigraphRegistryAddresses:
 async def validate_composition(
         spec_file: UploadFile = File(..., description="Composition JSON File"),
         simulators: List[str] = Query(..., description="Simulator package names to use for implementation"),
-        duration: int = Query(..., description="Duration of simulation"),
-):
+) -> ValidatedComposition:
     from process_bigraph import Composite
     from bsp import app_registrar
 
@@ -173,11 +177,12 @@ async def validate_composition(
             config={'state': document_data},
             core=app_registrar.core
         )
-        return {'state': composite.state}
+        return ValidatedComposition(state=composite.state, valid=True)
     except json.JSONDecodeError:
         raise HTTPException(status_code=400, detail="Invalid JSON format.")
     except Exception as e:
-        raise HTTPException(status_code=400, detail=str(e))
+        # raise HTTPException(status_code=400, detail=str(e))
+        return ValidatedComposition(state={'fail': str(e)}, valid=False)
 
 
 @app.post(
diff --git a/gateway/spec/openapi_3_1_0_generated.yaml b/gateway/spec/openapi_3_1_0_generated.yaml
index 6e8e7671e..b006e19ff 100644
--- a/gateway/spec/openapi_3_1_0_generated.yaml
+++ b/gateway/spec/openapi_3_1_0_generated.yaml
@@ -43,14 +43,6 @@ paths:
           description: Simulator package names to use for implementation
           title: Simulators
         description: Simulator package names to use for implementation
-      - name: duration
-        in: query
-        required: true
-        schema:
-          type: integer
-          description: Duration of simulation
-          title: Duration
-        description: Duration of simulation
       requestBody:
         required: true
         content:
@@ -62,7 +54,8 @@ paths:
           description: Successful Response
           content:
             application/json:
-              schema: {}
+              schema:
+                $ref: '#/components/schemas/ValidatedComposition'
         '422':
           description: Validation Error
           content:
@@ -267,6 +260,19 @@ components:
       - last_updated
       - results
       title: OutputData
+    ValidatedComposition:
+      properties:
+        state:
+          type: object
+          title: State
+        valid:
+          type: boolean
+          title: Valid
+      type: object
+      required:
+      - state
+      - valid
+      title: ValidatedComposition
     ValidationError:
       properties:
         loc:
diff --git a/kustomize/overlays/compose/kustomization.yaml b/kustomize/overlays/compose/kustomization.yaml
index 516e3bc25..5d1dc6ff3 100644
--- a/kustomize/overlays/compose/kustomization.yaml
+++ b/kustomize/overlays/compose/kustomization.yaml
@@ -8,7 +8,7 @@ images:
 - name: mongo
   newTag: 8.0-rc
 - name: ghcr.io/biosimulators/bio-compose-server-gateway
-  newTag: 0.0.5-dev
+  newTag: 0.0.6-dev
 - name: ghcr.io/biosimulators/bio-compose-server-worker
   newTag: 0.0.2-dev
 
diff --git a/shared/data_model.py b/shared/data_model.py
index 89d8e89d5..f3cd64340 100644
--- a/shared/data_model.py
+++ b/shared/data_model.py
@@ -221,3 +221,9 @@ class OutputData(BaseClass):
     status: str
     last_updated: str
     results: Dict
+
+
+@dataclass
+class ValidatedComposition(BaseClass):
+    state: Dict[str, Any]
+    valid: bool