diff --git a/src/clients/openai.rs b/src/clients/openai.rs
index 4a660a5d..3bea007e 100644
--- a/src/clients/openai.rs
+++ b/src/clients/openai.rs
@@ -386,10 +386,21 @@ pub struct JsonSchemaObject {
     pub required: Option<Vec<String>>,
 }
 
+#[derive(Debug, Clone, Default, Serialize, Deserialize, PartialEq)]
+#[serde(rename_all = "lowercase")]
+pub enum Role {
+    #[default]
+    User,
+    Developer,
+    Assistant,
+    System,
+    Tool,
+}
+
 #[derive(Debug, Default, Clone, Serialize, Deserialize)]
 pub struct Message {
-    /// The role of the messages author.
-    pub role: String,
+    /// The role of the author of this message.
+    pub role: Role,
     /// The contents of the message.
     #[serde(skip_serializing_if = "Option::is_none")]
     pub content: Option<Content>,
@@ -552,7 +563,7 @@ pub struct ChatCompletionChoice {
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct ChatCompletionMessage {
     /// The role of the author of this message.
-    pub role: String,
+    pub role: Role,
     /// The contents of the message.
     pub content: Option<String>,
     /// The tool calls generated by the model, such as function calls.
@@ -635,7 +646,7 @@ pub struct ChatCompletionChunkChoice {
 pub struct ChatCompletionDelta {
     /// The role of the author of this message.
     #[serde(skip_serializing_if = "Option::is_none")]
-    pub role: Option<String>,
+    pub role: Option<Role>,
     /// The contents of the message.
     #[serde(skip_serializing_if = "Option::is_none")]
     pub content: Option<String>,
diff --git a/src/orchestrator/chat_completions_detection.rs b/src/orchestrator/chat_completions_detection.rs
index 1b40c9eb..13519326 100644
--- a/src/orchestrator/chat_completions_detection.rs
+++ b/src/orchestrator/chat_completions_detection.rs
@@ -32,7 +32,7 @@ use crate::{
         detector::{ChatDetectionRequest, ContentAnalysisRequest},
         openai::{
             ChatCompletion, ChatCompletionChoice, ChatCompletionsRequest, ChatCompletionsResponse,
-            ChatDetections, Content, InputDetectionResult, OpenAiClient, OrchestratorWarning,
+            ChatDetections, Content, InputDetectionResult, OpenAiClient, OrchestratorWarning, Role,
         },
     },
     config::DetectorType,
@@ -51,7 +51,7 @@ pub struct ChatMessageInternal {
     /// Index of the message
     pub message_index: usize,
     /// The role of the messages author.
-    pub role: String,
+    pub role: Role,
     /// The contents of the message.
     #[serde(skip_serializing_if = "Option::is_none")]
     pub content: Option<Content>,
@@ -425,7 +425,7 @@ mod tests {
         let messages = vec![ChatMessageInternal {
             message_index: 0,
             content: Some(Content::Text("hello".to_string())),
-            role: "assistant".to_string(),
+            role: Role::Assistant,
             ..Default::default()
         }];
         let processed_messages = preprocess_chat_messages(&ctx, &detectors, messages).unwrap();
@@ -458,7 +458,7 @@ mod tests {
             message_index: 0,
             content: Some(Content::Text("hello".to_string())),
             // Invalid role will return error used for testing
-            role: "foo".to_string(),
+            role: Role::Tool,
             ..Default::default()
         }];
 
diff --git a/src/orchestrator/detector_processing/content.rs b/src/orchestrator/detector_processing/content.rs
index 96cca597..74f7bc9a 100644
--- a/src/orchestrator/detector_processing/content.rs
+++ b/src/orchestrator/detector_processing/content.rs
@@ -15,7 +15,8 @@
 
 */
 use crate::{
-    clients::openai::Content, models::ValidationError,
+    clients::openai::{Content, Role},
+    models::ValidationError,
     orchestrator::chat_completions_detection::ChatMessageInternal,
 };
 
@@ -38,7 +39,7 @@ pub fn filter_chat_messages(
         ));
     }
     // 2. Role is user | assistant | system
-    if !matches!(message.role.as_str(), "user" | "assistant" | "system") {
+    if !matches!(message.role, Role::User | Role::Assistant | Role::System) {
         return Err(ValidationError::Invalid(
             "Last message role must be user, assistant, or system".into(),
         ));
@@ -62,7 +63,7 @@ mod tests {
         let message = vec![ChatMessageInternal {
             message_index: 0,
             content: Some(Content::Text("hello".to_string())),
-            role: "assistant".to_string(),
+            role: Role::Assistant,
             ..Default::default()
         }];
 
@@ -79,13 +80,13 @@ mod tests {
             ChatMessageInternal {
                 message_index: 0,
                 content: Some(Content::Text("hello".to_string())),
-                role: "assistant".to_string(),
+                role: Role::Assistant,
                 ..Default::default()
             },
             ChatMessageInternal {
                 message_index: 1,
                 content: Some(Content::Text("bot".to_string())),
-                role: "assistant".to_string(),
+                role: Role::Assistant,
                 ..Default::default()
             },
         ];
@@ -102,7 +103,7 @@ mod tests {
         let message = vec![ChatMessageInternal {
             message_index: 0,
             content: Some(Content::Text("hello".to_string())),
-            role: "invalid_role".to_string(),
+            role: Role::Tool,
             ..Default::default()
         }];