diff --git a/docs/devel_doc/openapi.json b/docs/devel_doc/openapi.json
index e08a4b73c..b0f9e4f72 100644
--- a/docs/devel_doc/openapi.json
+++ b/docs/devel_doc/openapi.json
@@ -14449,6 +14449,12 @@
                                 "type": "null"
                             }
                         ]
+                    },
+                    "responses_request_max_size": {
+                        "type": "integer",
+                        "title": "Maximum character length for the serialized responses request body",
+                        "description": "Maximum character length for the serialized /v1/response responses request body",
+                        "default": 65536
                     }
                 },
                 "additionalProperties": false,
diff --git a/docs/models/requests.json b/docs/models/requests.json
index cea912e65..d6826e607 100644
--- a/docs/models/requests.json
+++ b/docs/models/requests.json
@@ -3165,4 +3165,4 @@
         }
     },
     "paths": {}
-}
+}
\ No newline at end of file
diff --git a/docs/models/successful_responses.json b/docs/models/successful_responses.json
index 6dfbbc952..7bac00cd7 100644
--- a/docs/models/successful_responses.json
+++ b/docs/models/successful_responses.json
@@ -1789,6 +1789,12 @@
                             }
                         ],
                         "default": null
+                    },
+                    "responses_request_max_size": {
+                        "default": 65536,
+                        "description": "Maximum character length for the serialized /v1/response responses request body",
+                        "title": "Maximum character length for the serialized responses request body",
+                        "type": "integer"
                     }
                 },
                 "title": "Customization",
diff --git a/docs/models/successful_responses.md b/docs/models/successful_responses.md
index e8ee4cb3a..425f54bc6 100644
--- a/docs/models/successful_responses.md
+++ b/docs/models/successful_responses.md
@@ -684,6 +684,7 @@ Service customization.
 | agent_card_path | string |  |
 | agent_card_config | object |  |
 | custom_profile |  |  |
+| responses_request_max_size | integer | Maximum character length for the serialized /v1/response responses request body |
 
 
 ## DatabaseConfiguration
diff --git a/src/models/config.py b/src/models/config.py
index 7fae4a9c8..da2b734c1 100644
--- a/src/models/config.py
+++ b/src/models/config.py
@@ -1963,6 +1963,12 @@ class Customization(ConfigurationBase):
     agent_card_path: Optional[FilePath] = None
     agent_card_config: Optional[dict[str, Any]] = None
     custom_profile: Optional[CustomProfile] = Field(default=None, init=False)
+    responses_request_max_size: int = Field(
+        default=constants.RESPONSES_REQUEST_MAX_SIZE,
+        title="Maximum character length for the serialized responses request body",
+        description="Maximum character length for the serialized /v1/response responses "
+        "request body",
+    )
 
     @model_validator(mode="after")
     def check_customization_model(self) -> Self:
diff --git a/tests/unit/models/config/test_customization.py b/tests/unit/models/config/test_customization.py
index daca3206e..ad2f72e6b 100644
--- a/tests/unit/models/config/test_customization.py
+++ b/tests/unit/models/config/test_customization.py
@@ -6,6 +6,7 @@
 from pydantic import ValidationError
 from pytest_subtests import SubTests
 
+from constants import RESPONSES_REQUEST_MAX_SIZE
 from models.config import Customization
 
 
@@ -58,6 +59,21 @@ def test_service_customization(subtests: SubTests) -> None:
         assert c.disable_query_system_prompt is True
 
 
+def test_service_customization_max_response_request_size(subtests: SubTests) -> None:
+    """Check the service customization class."""
+    with subtests.test(msg="Default response request size should be used"):
+        c = Customization()
+        assert c is not None
+        # default value should not be used now
+        assert c.responses_request_max_size == RESPONSES_REQUEST_MAX_SIZE
+
+    with subtests.test(msg="Max response request size is specified"):
+        c = Customization(responses_request_max_size=42)
+        assert c is not None
+        # default value should not be used now
+        assert c.responses_request_max_size == 42
+
+
 def test_service_customization_wrong_system_prompt_path() -> None:
     """Check the service customization class.