diff --git a/api/specs/web-server/_common.py b/api/specs/web-server/_common.py
index 7c0f3c97d44..505e525c4f4 100644
--- a/api/specs/web-server/_common.py
+++ b/api/specs/web-server/_common.py
@@ -12,7 +12,7 @@
 from common_library.pydantic_fields_extension import get_type
 from fastapi import FastAPI, Query
 from models_library.basic_types import LogLevel
-from pydantic import BaseModel, ConfigDict, Field, create_model
+from pydantic import BaseModel, ConfigDict, Field, Json, create_model
 from pydantic.fields import FieldInfo
 from servicelib.fastapi.openapi import override_fastapi_openapi_method
 
@@ -77,7 +77,7 @@ def as_query(model_class: type[BaseModel]) -> type[BaseModel]:
             "json_schema_extra": field_info.json_schema_extra or {},
         }
 
-        json_field_type = str
+        json_field_type = Json
         # _create_json_type(
         #    description=query_kwargs["description"],
         #    example=query_kwargs.get("json_schema_extra", {}).get("example_json"),
diff --git a/services/web/server/src/simcore_service_webserver/api/v0/openapi.yaml b/services/web/server/src/simcore_service_webserver/api/v0/openapi.yaml
index 3a32e4cb7ba..906c7016ec2 100644
--- a/services/web/server/src/simcore_service_webserver/api/v0/openapi.yaml
+++ b/services/web/server/src/simcore_service_webserver/api/v0/openapi.yaml
@@ -2625,6 +2625,8 @@ paths:
         schema:
           anyOf:
           - type: string
+            contentMediaType: application/json
+            contentSchema: {}
           - type: 'null'
           title: Filters
       - name: order_by
@@ -2632,6 +2634,8 @@ paths:
         required: false
         schema:
           type: string
+          contentMediaType: application/json
+          contentSchema: {}
           default: '{"field":"modified","direction":"desc"}'
           title: Order By
       - name: limit
@@ -2688,6 +2692,8 @@ paths:
         schema:
           anyOf:
           - type: string
+            contentMediaType: application/json
+            contentSchema: {}
           - type: 'null'
           title: Filters
       - name: order_by
@@ -2695,6 +2701,8 @@ paths:
         required: false
         schema:
           type: string
+          contentMediaType: application/json
+          contentSchema: {}
           default: '{"field":"modified","direction":"desc"}'
           title: Order By
       - name: limit
@@ -3234,6 +3242,8 @@ paths:
         schema:
           anyOf:
           - type: string
+            contentMediaType: application/json
+            contentSchema: {}
           - type: 'null'
           title: Filters
       - name: order_by
@@ -3241,6 +3251,8 @@ paths:
         required: false
         schema:
           type: string
+          contentMediaType: application/json
+          contentSchema: {}
           default: '{"field":"last_change_date","direction":"desc"}'
           title: Order By
       - name: limit
@@ -3376,6 +3388,8 @@ paths:
         required: false
         schema:
           type: string
+          contentMediaType: application/json
+          contentSchema: {}
           default: '{"field":"last_change_date","direction":"desc"}'
           title: Order By
       - name: limit
@@ -4382,7 +4396,7 @@ paths:
         '403':
           description: ProjectInvalidRightsError
         '404':
-          description: UserDefaultWalletNotFoundError, ProjectNotFoundError
+          description: ProjectNotFoundError, UserDefaultWalletNotFoundError
         '409':
           description: ProjectTooManyProjectOpenedError
         '422':
@@ -4605,6 +4619,8 @@ paths:
         required: false
         schema:
           type: string
+          contentMediaType: application/json
+          contentSchema: {}
           default: '{"field":"started_at","direction":"desc"}'
           title: Order By
       - name: wallet_id
@@ -4624,8 +4640,7 @@ paths:
           anyOf:
           - type: string
             contentMediaType: application/json
-            contentSchema:
-              type: string
+            contentSchema: {}
           - type: 'null'
           title: Filters
       - name: limit
@@ -4709,6 +4724,8 @@ paths:
         required: false
         schema:
           type: string
+          contentMediaType: application/json
+          contentSchema: {}
           default: '{"field":"started_at","direction":"desc"}'
           title: Order By
       - name: wallet_id
@@ -4728,8 +4745,7 @@ paths:
           anyOf:
           - type: string
             contentMediaType: application/json
-            contentSchema:
-              type: string
+            contentSchema: {}
           - type: 'null'
           title: Filters
       responses: