diff --git a/app/schema.graphql b/app/schema.graphql
index 7d78c9a9ac..ce485960fb 100644
--- a/app/schema.graphql
+++ b/app/schema.graphql
@@ -1401,6 +1401,10 @@ type PromptChatTemplate {
   messages: [PromptTemplateMessage!]!
 }
 
+input PromptChatTemplateInput {
+  messages: [TextPromptMessageInput!]!
+}
+
 """A connection to a list of items."""
 type PromptConnection {
   """Pagination data for this connection"""
@@ -1491,7 +1495,7 @@ input PromptVersionInput {
   description: String = null
   templateType: PromptTemplateType!
   templateFormat: PromptTemplateFormat!
-  template: JSON!
+  template: PromptChatTemplateInput!
   invocationParameters: JSON! = {}
   tools: [ToolDefinitionInput!]! = []
   outputSchema: JSONSchemaInput = null
@@ -1847,6 +1851,11 @@ type TextPromptMessage {
   content: String!
 }
 
+input TextPromptMessageInput {
+  role: PromptMessageRole!
+  content: String!
+}
+
 input TimeRange {
   """The start of the time range"""
   start: DateTime!
diff --git a/src/phoenix/server/api/input_types/PromptVersionInput.py b/src/phoenix/server/api/input_types/PromptVersionInput.py
index 3bde6c7abf..9d0f77e086 100644
--- a/src/phoenix/server/api/input_types/PromptVersionInput.py
+++ b/src/phoenix/server/api/input_types/PromptVersionInput.py
@@ -4,15 +4,15 @@
 from strawberry.scalars import JSON
 
 from phoenix.server.api.helpers.prompts.models import (
+    PromptChatTemplateV1,
     PromptTemplateFormat,
     PromptTemplateType,
-)
-from phoenix.server.api.helpers.prompts.models import (
-    PromptToolDefinition as ToolDefinitionModel,
+    PromptToolDefinition,
+    TextPromptMessage,
 )
 
 
-@strawberry.experimental.pydantic.input(ToolDefinitionModel)
+@strawberry.experimental.pydantic.input(PromptToolDefinition)
 class ToolDefinitionInput:
     definition: JSON
 
@@ -22,12 +22,23 @@ class JSONSchemaInput:
     definition: JSON
 
 
+@strawberry.experimental.pydantic.input(TextPromptMessage)
+class TextPromptMessageInput:
+    role: strawberry.auto
+    content: strawberry.auto
+
+
+@strawberry.experimental.pydantic.input(PromptChatTemplateV1)
+class PromptChatTemplateInput:
+    messages: list[TextPromptMessageInput]
+
+
 @strawberry.input
 class PromptVersionInput:
     description: Optional[str] = None
     template_type: PromptTemplateType
     template_format: PromptTemplateFormat
-    template: JSON
+    template: PromptChatTemplateInput
     invocation_parameters: JSON = strawberry.field(default_factory=dict)
     tools: list[ToolDefinitionInput] = strawberry.field(default_factory=list)
     output_schema: Optional[JSONSchemaInput] = None
diff --git a/src/phoenix/server/api/mutations/prompt_mutations.py b/src/phoenix/server/api/mutations/prompt_mutations.py
index 2e8a623bcd..47247fc466 100644
--- a/src/phoenix/server/api/mutations/prompt_mutations.py
+++ b/src/phoenix/server/api/mutations/prompt_mutations.py
@@ -46,7 +46,9 @@ async def create_prompt(self, info: Info[Context, None], input: CreatePromptInpu
                 if input.prompt_version.output_schema is not None
                 else None
             )
-            template = PromptChatTemplateV1.model_validate(input.prompt_version.template).dict()
+            template = PromptChatTemplateV1.model_validate(
+                strawberry.asdict(input.prompt_version.template)
+            ).dict()
         except ValidationError as error:
             raise BadRequest(str(error))
         async with info.context.db() as session:
diff --git a/tests/unit/server/api/mutations/test_prompt_mutations.py b/tests/unit/server/api/mutations/test_prompt_mutations.py
index 0f5c2b760e..4fcaf2699b 100644
--- a/tests/unit/server/api/mutations/test_prompt_mutations.py
+++ b/tests/unit/server/api/mutations/test_prompt_mutations.py
@@ -58,7 +58,7 @@ class TestPromptMutations:
                             "description": "prompt-version-description",
                             "templateType": "CHAT",
                             "templateFormat": "MUSTACHE",
-                            "template": {"messages": [{"role": "user", "content": "hello world"}]},
+                            "template": {"messages": [{"role": "USER", "content": "hello world"}]},
                             "invocationParameters": {"temperature": 0.4},
                             "modelProvider": "openai",
                             "modelName": "o1-mini",
@@ -78,7 +78,7 @@ class TestPromptMutations:
                             "description": "prompt-version-description",
                             "templateType": "CHAT",
                             "templateFormat": "MUSTACHE",
-                            "template": {"messages": [{"role": "user", "content": "hello world"}]},
+                            "template": {"messages": [{"role": "USER", "content": "hello world"}]},
                             "invocationParameters": {"temperature": 0.4},
                             "modelProvider": "openai",
                             "modelName": "o1-mini",
@@ -99,7 +99,7 @@ class TestPromptMutations:
                             "description": "prompt-version-description",
                             "templateType": "CHAT",
                             "templateFormat": "MUSTACHE",
-                            "template": {"messages": [{"role": "user", "content": "hello world"}]},
+                            "template": {"messages": [{"role": "USER", "content": "hello world"}]},
                             "invocationParameters": {"temperature": 0.4},
                             "modelProvider": "openai",
                             "modelName": "o1-mini",
@@ -163,7 +163,7 @@ async def test_create_prompt_fails_on_name_conflict(
                     "description": "prompt-version-description",
                     "templateType": "CHAT",
                     "templateFormat": "MUSTACHE",
-                    "template": {"messages": [{"role": "user", "content": "hello world"}]},
+                    "template": {"messages": [{"role": "USER", "content": "hello world"}]},
                     "invocationParameters": {"temperature": 0.4},
                     "modelProvider": "openai",
                     "modelName": "o1-mini",
@@ -183,33 +183,6 @@ async def test_create_prompt_fails_on_name_conflict(
     @pytest.mark.parametrize(
         "variables,expected_error",
         [
-            pytest.param(
-                {
-                    "input": {
-                        "name": "another-prompt-name",
-                        "description": "prompt-description",
-                        "promptVersion": {
-                            "description": "prompt-version-description",
-                            "templateType": "CHAT",
-                            "templateFormat": "MUSTACHE",
-                            "template": {
-                                "messages": [
-                                    {
-                                        "role": "user",
-                                        "content": "hello world",
-                                        "extra_key": "test_value",
-                                    }
-                                ]
-                            },
-                            "invocationParameters": {"temperature": 0.4},
-                            "modelProvider": "openai",
-                            "modelName": "o1-mini",
-                        },
-                    }
-                },
-                "extra_key",
-                id="extra-key-in-message",
-            ),
             pytest.param(
                 {
                     "input": {
@@ -219,7 +192,7 @@ async def test_create_prompt_fails_on_name_conflict(
                             "description": "prompt-version-description",
                             "templateType": "CHAT",
                             "templateFormat": "MUSTACHE",
-                            "template": {"messages": [{"role": "user", "content": "hello world"}]},
+                            "template": {"messages": [{"role": "USER", "content": "hello world"}]},
                             "invocationParameters": {"temperature": 0.4},
                             "modelProvider": "openai",
                             "modelName": "o1-mini",
@@ -241,7 +214,7 @@ async def test_create_prompt_fails_on_name_conflict(
                             "description": "prompt-version-description",
                             "templateType": "CHAT",
                             "templateFormat": "MUSTACHE",
-                            "template": {"messages": [{"role": "user", "content": "hello world"}]},
+                            "template": {"messages": [{"role": "USER", "content": "hello world"}]},
                             "invocationParameters": {"temperature": 0.4},
                             "modelProvider": "openai",
                             "modelName": "o1-mini",