diff --git a/docs/resources/llama-stack-spec.html b/docs/resources/llama-stack-spec.html
index 0454e22ec..82493b69f 100644
--- a/docs/resources/llama-stack-spec.html
+++ b/docs/resources/llama-stack-spec.html
@@ -2439,7 +2439,8 @@
                     "type": {
                         "type": "string",
                         "const": "image",
-                        "default": "image"
+                        "default": "image",
+                        "description": "Discriminator type of the content item. Always \"image\""
                     },
                     "image": {
                         "type": "object",
@@ -2448,18 +2449,19 @@
                                 "$ref": "#/components/schemas/URL"
                             },
                             "data": {
-                                "type": "string",
-                                "contentEncoding": "base64"
+                                "type": "string"
                             }
                         },
-                        "additionalProperties": false
+                        "additionalProperties": false,
+                        "description": "Image as a base64 encoded string or an URL"
                     }
                 },
                 "additionalProperties": false,
                 "required": [
                     "type",
                     "image"
-                ]
+                ],
+                "title": "A image content item"
             },
             "InterleavedContent": {
                 "oneOf": [
@@ -2647,17 +2649,20 @@
                     "type": {
                         "type": "string",
                         "const": "text",
-                        "default": "text"
+                        "default": "text",
+                        "description": "Discriminator type of the content item. Always \"text\""
                     },
                     "text": {
-                        "type": "string"
+                        "type": "string",
+                        "description": "Text content"
                     }
                 },
                 "additionalProperties": false,
                 "required": [
                     "type",
                     "text"
-                ]
+                ],
+                "title": "A text content item"
             },
             "ToolCall": {
                 "type": "object",
diff --git a/docs/resources/llama-stack-spec.yaml b/docs/resources/llama-stack-spec.yaml
index 0734ef236..71e2b8ed9 100644
--- a/docs/resources/llama-stack-spec.yaml
+++ b/docs/resources/llama-stack-spec.yaml
@@ -1466,6 +1466,8 @@ components:
           type: string
           const: image
           default: image
+          description: >-
+            Discriminator type of the content item. Always "image"
         image:
           type: object
           properties:
@@ -1473,12 +1475,14 @@ components:
               $ref: '#/components/schemas/URL'
             data:
               type: string
-              contentEncoding: base64
           additionalProperties: false
+          description: >-
+            Image as a base64 encoded string or an URL
       additionalProperties: false
       required:
         - type
         - image
+      title: A image content item
     InterleavedContent:
       oneOf:
         - type: string
@@ -1598,12 +1602,16 @@ components:
           type: string
           const: text
           default: text
+          description: >-
+            Discriminator type of the content item. Always "text"
         text:
           type: string
+          description: Text content
       additionalProperties: false
       required:
         - type
         - text
+      title: A text content item
     ToolCall:
       type: object
       properties:
diff --git a/llama_stack/apis/common/content_types.py b/llama_stack/apis/common/content_types.py
index 0b27a0196..3cb901924 100644
--- a/llama_stack/apis/common/content_types.py
+++ b/llama_stack/apis/common/content_types.py
@@ -4,14 +4,13 @@
 # This source code is licensed under the terms described in the LICENSE file in
 # the root directory of this source tree.
 
-import base64
 from enum import Enum
 from typing import Annotated, List, Literal, Optional, Union
 
 from llama_models.llama3.api.datatypes import ToolCall
 
 from llama_models.schema_utils import json_schema_type, register_schema
-from pydantic import BaseModel, Field, field_serializer, model_validator
+from pydantic import BaseModel, Field, model_validator
 
 
 @json_schema_type
@@ -21,7 +20,8 @@ class URL(BaseModel):
 
 class _URLOrData(BaseModel):
     url: Optional[URL] = None
-    data: Optional[bytes] = None
+    # data is a base64 encoded string
+    data: Optional[str] = None
 
     @model_validator(mode="before")
     @classmethod
@@ -30,21 +30,27 @@ class _URLOrData(BaseModel):
             return values
         return {"url": values}
 
-    @field_serializer("data")
-    def serialize_data(self, data: Optional[bytes], _info):
-        if data is None:
-            return None
-        return base64.b64encode(data).decode("utf-8")
-
 
 @json_schema_type
 class ImageContentItem(BaseModel):
+    """A image content item
+
+    :param type: Discriminator type of the content item. Always "image"
+    :param image: Image as a base64 encoded string or an URL
+    """
+
     type: Literal["image"] = "image"
     image: _URLOrData
 
 
 @json_schema_type
 class TextContentItem(BaseModel):
+    """A text content item
+
+    :param type: Discriminator type of the content item. Always "text"
+    :param text: Text content
+    """
+
     type: Literal["text"] = "text"
     text: str
 
diff --git a/llama_stack/providers/utils/inference/prompt_adapter.py b/llama_stack/providers/utils/inference/prompt_adapter.py
index f5298d844..babfb736a 100644
--- a/llama_stack/providers/utils/inference/prompt_adapter.py
+++ b/llama_stack/providers/utils/inference/prompt_adapter.py
@@ -135,7 +135,8 @@ async def interleaved_content_convert_to_raw(
                 else:
                     raise ValueError("Unsupported URL type")
             elif image.data:
-                data = image.data
+                # data is a base64 encoded string, decode it to bytes for RawMediaItem
+                data = base64.b64decode(image.data)
             else:
                 raise ValueError("No data or URL provided")