diff --git a/openapi/openapiv2.json b/openapi/openapiv2.json
index a2b3ac0a4..c0d6b230c 100644
--- a/openapi/openapiv2.json
+++ b/openapi/openapiv2.json
@@ -7590,6 +7590,21 @@
       },
       "title": "A subset of WorkerDeploymentInfo"
     },
+    "NamespaceInfoLimits": {
+      "type": "object",
+      "properties": {
+        "blobSizeLimitError": {
+          "type": "string",
+          "format": "int64",
+          "description": "Maximum size in bytes for payload fields in workflow history events\n(e.g., workflow/activity inputs and results, failure details, signal payloads).\nWhen exceeded, the server will reject the operation with an error."
+        },
+        "memoSizeLimitError": {
+          "type": "string",
+          "format": "int64",
+          "description": "Maximum total memo size in bytes per workflow execution."
+        }
+      }
+    },
     "OperatorServiceUpdateNexusEndpointBody": {
       "type": "object",
       "properties": {
@@ -12549,6 +12564,10 @@
           "$ref": "#/definitions/v1NamespaceInfoCapabilities",
           "description": "All capabilities the namespace supports."
         },
+        "limits": {
+          "$ref": "#/definitions/NamespaceInfoLimits",
+          "title": "Namespace configured limits"
+        },
         "supportsSchedules": {
           "type": "boolean",
           "description": "Whether scheduled workflows are supported on this namespace. This is only needed\ntemporarily while the feature is experimental, so we can give it a high tag."
diff --git a/openapi/openapiv3.yaml b/openapi/openapiv3.yaml
index d12d1d620..2d04d5270 100644
--- a/openapi/openapiv3.yaml
+++ b/openapi/openapiv3.yaml
@@ -9311,6 +9311,10 @@ components:
           allOf:
             - $ref: '#/components/schemas/NamespaceInfo_Capabilities'
           description: All capabilities the namespace supports.
+        limits:
+          allOf:
+            - $ref: '#/components/schemas/NamespaceInfo_Limits'
+          description: Namespace configured limits
         supportsSchedules:
           type: boolean
           description: |-
@@ -9335,6 +9339,18 @@ components:
           type: boolean
           description: True if the namespace supports reported problems search attribute
       description: Namespace capability details. Should contain what features are enabled in a namespace.
+    NamespaceInfo_Limits:
+      type: object
+      properties:
+        blobSizeLimitError:
+          type: string
+          description: |-
+            Maximum size in bytes for payload fields in workflow history events
+             (e.g., workflow/activity inputs and results, failure details, signal payloads).
+             When exceeded, the server will reject the operation with an error.
+        memoSizeLimitError:
+          type: string
+          description: Maximum total memo size in bytes per workflow execution.
     NamespaceReplicationConfig:
       type: object
       properties:
diff --git a/temporal/api/namespace/v1/message.proto b/temporal/api/namespace/v1/message.proto
index 79c44cb05..2774cc7fc 100644
--- a/temporal/api/namespace/v1/message.proto
+++ b/temporal/api/namespace/v1/message.proto
@@ -40,6 +40,17 @@ message NamespaceInfo {
         bool reported_problems_search_attribute = 5;
     }
 
+    // Namespace configured limits
+    Limits limits = 8;
+    message Limits {
+        // Maximum size in bytes for payload fields in workflow history events
+        // (e.g., workflow/activity inputs and results, failure details, signal payloads).
+        // When exceeded, the server will reject the operation with an error.
+        int64 blob_size_limit_error = 1;
+        // Maximum total memo size in bytes per workflow execution.
+        int64 memo_size_limit_error = 2;
+    }
+
     // Whether scheduled workflows are supported on this namespace. This is only needed
     // temporarily while the feature is experimental, so we can give it a high tag.
     bool supports_schedules = 100;