diff --git a/specification/ai/Azure.AI.Projects/client.tsp b/specification/ai/Azure.AI.Projects/client.tsp
index 37df92c81c9d..a6fe1125ebac 100644
--- a/specification/ai/Azure.AI.Projects/client.tsp
+++ b/specification/ai/Azure.AI.Projects/client.tsp
@@ -29,13 +29,6 @@ using Azure.ClientGenerator.Core;
 // More accurate naming
 @@clientName(Azure.AI.Projects.AssetCredentialResponse, "DatasetCredential");
 
-// In Python, the emitter changes "keys" to "keys_property", since there is already
-// a "keys" method in the generated code due to usage of MutableMapping. Call it credential_keys instead.
-@@clientName(Azure.AI.Projects.CustomCredential.keys,
-  "credential_keys",
-  "python"
-);
-
 // Less generic names for C# SDK (avoid one-word class names)
 @@clientName(Azure.AI.Projects.Connection, "ConnectionProperties", "csharp");
 @@clientName(Azure.AI.Projects.Deployment, "AssetDeployment", "csharp");
diff --git a/specification/ai/Azure.AI.Projects/connections/models.tsp b/specification/ai/Azure.AI.Projects/connections/models.tsp
index 31fc746544a6..991802e073e5 100644
--- a/specification/ai/Azure.AI.Projects/connections/models.tsp
+++ b/specification/ai/Azure.AI.Projects/connections/models.tsp
@@ -78,9 +78,8 @@ model CustomCredential extends BaseCredentials {
   @visibility(Lifecycle.Read)
   type: CredentialType.custom;
 
-  @doc("The credential type")
-  @visibility(Lifecycle.Read)
-  keys: Record<string>;
+  // Secret custom keys
+  ...Record<string>;
 }
 
 #suppress "@azure-tools/typespec-azure-core/casing-style"
diff --git a/specification/ai/data-plane/Azure.AI.Projects/preview/2025-05-15-preview/azure-ai-projects.json b/specification/ai/data-plane/Azure.AI.Projects/preview/2025-05-15-preview/azure-ai-projects.json
index cb475d40c91b..212e782194b9 100644
--- a/specification/ai/data-plane/Azure.AI.Projects/preview/2025-05-15-preview/azure-ai-projects.json
+++ b/specification/ai/data-plane/Azure.AI.Projects/preview/2025-05-15-preview/azure-ai-projects.json
@@ -2242,19 +2242,9 @@
     "CustomCredential": {
       "type": "object",
       "description": "Custom credential definition",
-      "properties": {
-        "keys": {
-          "type": "object",
-          "description": "The credential type",
-          "additionalProperties": {
-            "type": "string"
-          },
-          "readOnly": true
-        }
+      "additionalProperties": {
+        "type": "string"
       },
-      "required": [
-        "keys"
-      ],
       "allOf": [
         {
           "$ref": "#/definitions/BaseCredentials"
diff --git a/specification/ai/data-plane/Azure.AI.Projects/stable/2025-05-01/azure-ai-projects.json b/specification/ai/data-plane/Azure.AI.Projects/stable/2025-05-01/azure-ai-projects.json
index 193b940ec363..90038bb38da0 100644
--- a/specification/ai/data-plane/Azure.AI.Projects/stable/2025-05-01/azure-ai-projects.json
+++ b/specification/ai/data-plane/Azure.AI.Projects/stable/2025-05-01/azure-ai-projects.json
@@ -1443,19 +1443,9 @@
     "CustomCredential": {
       "type": "object",
       "description": "Custom credential definition",
-      "properties": {
-        "keys": {
-          "type": "object",
-          "description": "The credential type",
-          "additionalProperties": {
-            "type": "string"
-          },
-          "readOnly": true
-        }
+      "additionalProperties": {
+        "type": "string"
       },
-      "required": [
-        "keys"
-      ],
       "allOf": [
         {
           "$ref": "#/definitions/BaseCredentials"
diff --git a/specification/ai/data-plane/Azure.AI.Projects/stable/v1/azure-ai-projects.json b/specification/ai/data-plane/Azure.AI.Projects/stable/v1/azure-ai-projects.json
index 5552a96b7d1a..9c60c074418f 100644
--- a/specification/ai/data-plane/Azure.AI.Projects/stable/v1/azure-ai-projects.json
+++ b/specification/ai/data-plane/Azure.AI.Projects/stable/v1/azure-ai-projects.json
@@ -1443,19 +1443,9 @@
     "CustomCredential": {
       "type": "object",
       "description": "Custom credential definition",
-      "properties": {
-        "keys": {
-          "type": "object",
-          "description": "The credential type",
-          "additionalProperties": {
-            "type": "string"
-          },
-          "readOnly": true
-        }
+      "additionalProperties": {
+        "type": "string"
       },
-      "required": [
-        "keys"
-      ],
       "allOf": [
         {
           "$ref": "#/definitions/BaseCredentials"