diff --git a/proto/generate.proto b/proto/generate.proto
index 916a1716b..f91812fc9 100644
--- a/proto/generate.proto
+++ b/proto/generate.proto
@@ -17,7 +17,7 @@ service LoraxService {
     rpc Prefill (PrefillRequest) returns (PrefillResponse);
     /// Embed
     rpc Embed (EmbedRequest) returns (EmbedResponse);
-    /// Classify 
+    /// Classify
     rpc Classify (ClassifyRequest) returns (ClassifyResponse);
     /// Decode token for a list of prefilled batches
     rpc Decode (DecodeRequest) returns (DecodeResponse);
@@ -58,6 +58,7 @@ message InfoResponse {
     bool supports_embeddings = 9;
     bool supports_classification = 10;
     bool chunked_prefill = 11;
+    bool requires_block_allocator = 12;
 }
 
 /// Empty request
@@ -118,11 +119,11 @@ message StoppingCriteriaParameters {
 message Image {
     /// Binary image data.
     bytes data = 1;
-  
+
     /// Image MIME type.
     string mimetype = 2;
   }
-  
+
 message InputChunk {
     oneof chunk {
       /// Plain text data
@@ -331,7 +332,7 @@ message Entity {
 message EntityList {
     /// Request ID
     uint64 request_id = 1;
-    /// Entities 
+    /// Entities
     repeated Entity entities = 2;
     /// XXX
     repeated uint32 input_ids = 4;
diff --git a/router/src/infer.rs b/router/src/infer.rs
index 2833cd485..a142793d8 100644
--- a/router/src/infer.rs
+++ b/router/src/infer.rs
@@ -188,7 +188,7 @@ impl Infer {
         preloaded_adapters: Vec<PreloadedAdapter>,
         prefix_caching: bool,
         chunked_prefill: bool,
-        is_causal_lm: bool,
+        requires_block_allocator: bool,
     ) -> Self {
         let adapter_event = Arc::new(AdapterEvent {
             batching_task: Notify::new(),
@@ -207,7 +207,7 @@ impl Infer {
             max_batch_total_tokens,
             prefix_caching,
             chunked_prefill,
-            is_causal_lm,
+            requires_block_allocator,
         );
 
         // Initialize with base model adapter (empty) mapping to index 0
@@ -501,10 +501,12 @@ impl Infer {
                 err
             })?;
 
+        let embed_params = request.parameters.unwrap_or_default();
+
         let (adapter_source, adapter_parameters) = extract_adapter_params(
-            request.parameters.adapter_id.clone(),
-            request.parameters.adapter_source.clone(),
-            request.parameters.adapter_parameters.clone(),
+            embed_params.adapter_id.clone(),
+            embed_params.adapter_source.clone(),
+            embed_params.adapter_parameters.clone(),
         );
 
         let adapter_idx;
@@ -520,7 +522,7 @@ impl Infer {
             }
         }
 
-        let api_token = request.parameters.api_token.clone();
+        let api_token = embed_params.api_token.clone();
         let adapter = Adapter::new(
             adapter_parameters,
             adapter_source.unwrap(),
@@ -875,10 +877,12 @@ impl Infer {
                 err
             })?;
 
+        let embed_params = request.parameters.clone().unwrap_or_default();
+
         let (adapter_source, adapter_parameters) = extract_adapter_params(
-            request.parameters.adapter_id.clone(),
-            request.parameters.adapter_source.clone(),
-            request.parameters.adapter_parameters.clone(),
+            embed_params.adapter_id.clone(),
+            embed_params.adapter_source.clone(),
+            embed_params.adapter_parameters.clone(),
         );
 
         let adapter_idx;
@@ -894,7 +898,7 @@ impl Infer {
             }
         }
 
-        let api_token = request.parameters.api_token.clone();
+        let api_token = embed_params.api_token.clone();
         let adapter = Adapter::new(
             adapter_parameters,
             adapter_source.unwrap(),
diff --git a/router/src/lib.rs b/router/src/lib.rs
index fd5b1049f..c3cf2cedc 100644
--- a/router/src/lib.rs
+++ b/router/src/lib.rs
@@ -1144,20 +1144,22 @@ pub(crate) struct EmbedParameters {
     pub api_token: Option<String>,
 }
 
-fn default_embed_parameters() -> EmbedParameters {
-    EmbedParameters {
-        adapter_id: None,
-        adapter_source: None,
-        adapter_parameters: None,
-        api_token: None,
+impl Default for EmbedParameters {
+    fn default() -> Self {
+        Self {
+            adapter_id: None,
+            adapter_source: None,
+            adapter_parameters: None,
+            api_token: None,
+        }
     }
 }
 
 #[derive(Clone, Debug, Deserialize, ToSchema)]
 struct EmbedRequest {
     inputs: String,
-    #[serde(default = "default_embed_parameters")]
-    pub parameters: EmbedParameters,
+    #[serde(default)]
+    pub parameters: Option<EmbedParameters>,
 }
 
 #[derive(Serialize, ToSchema)]
@@ -1192,8 +1194,8 @@ struct CompatEmbedRequest {
     dimensions: Option<i32>,
     #[allow(dead_code)]
     user: Option<String>,
-    #[serde(default = "default_embed_parameters")]
-    parameters: EmbedParameters,
+    #[serde(default)]
+    parameters: Option<EmbedParameters>,
 }
 
 #[derive(Serialize, ToSchema)]
@@ -1221,8 +1223,8 @@ struct BatchClassifyRequest {
 #[derive(Clone, Debug, Deserialize, ToSchema)]
 struct BatchEmbedRequest {
     inputs: Vec<String>,
-    #[serde(default = "default_embed_parameters")]
-    parameters: EmbedParameters,
+    #[serde(default)]
+    parameters: Option<EmbedParameters>,
 }
 
 #[derive(Debug, Serialize, Deserialize)]
diff --git a/router/src/scheduler.rs b/router/src/scheduler.rs
index 9b2514623..cca4b05a1 100644
--- a/router/src/scheduler.rs
+++ b/router/src/scheduler.rs
@@ -41,7 +41,7 @@ impl AdapterScheduler {
         max_batch_total_tokens: u32,
         prefix_caching: bool,
         chunked_prefill: bool,
-        is_causal_lm: bool,
+        requires_block_allocator: bool,
     ) -> Self {
         let (sender, receiver) = mpsc::unbounded_channel();
 
@@ -59,7 +59,7 @@ impl AdapterScheduler {
             max_batch_total_tokens,
             prefix_caching,
             chunked_prefill,
-            is_causal_lm,
+            requires_block_allocator,
         ));
 
         Self { sender }
@@ -125,7 +125,7 @@ async fn adapter_scheduler_task(
     max_batch_total_tokens: u32,
     prefix_caching: bool,
     chunked_prefill: bool,
-    is_causal_lm: bool,
+    requires_block_allocator: bool,
 ) {
     let mut state = AdapterSchedulerState::new(
         client,
@@ -138,7 +138,7 @@ async fn adapter_scheduler_task(
         max_batch_total_tokens,
         prefix_caching,
         chunked_prefill,
-        is_causal_lm,
+        requires_block_allocator,
     );
 
     while let Some(cmd) = receiver.recv().await {
@@ -217,7 +217,7 @@ impl AdapterSchedulerState {
         max_batch_total_tokens: u32,
         prefix_caching: bool,
         chunked_prefill: bool,
-        is_causal_lm: bool,
+        requires_block_allocator: bool,
     ) -> Self {
         let queues_state = Arc::new(Mutex::new(AdapterQueuesState::new(
             max_active_adapters,
@@ -226,7 +226,7 @@ impl AdapterSchedulerState {
         let loader = AdapterLoader::new(client.clone());
 
         // Only causal LMs require the block allocator, due to paged attention
-        let block_allocator = (!requires_padding && is_causal_lm).then(|| {
+        let block_allocator = (!requires_padding && requires_block_allocator).then(|| {
             BlockAllocator::new(
                 max_batch_total_tokens,
                 block_size,
diff --git a/router/src/server.rs b/router/src/server.rs
index 28d56efd8..405bcff84 100644
--- a/router/src/server.rs
+++ b/router/src/server.rs
@@ -486,12 +486,12 @@ async fn health(
     if health.shard_info().supports_embeddings {
         let embed_request = EmbedRequest {
             inputs: "San Francisco".to_string(),
-            parameters: EmbedParameters {
+            parameters: Some(EmbedParameters {
                 adapter_id: None,
                 adapter_source: None,
                 adapter_parameters: None,
                 api_token: None,
-            },
+            }),
         };
         match infer.embed(embed_request).await {
             Ok(_) => {}
@@ -1354,7 +1354,7 @@ pub async fn run(
         shard_info.preloaded_adapters,
         prefix_caching,
         shard_info.chunked_prefill,
-        is_causal_lm,
+        shard_info.requires_block_allocator,
     );
 
     // Duration buckets
diff --git a/router/src/validation.rs b/router/src/validation.rs
index 34c564541..e4194a1fb 100644
--- a/router/src/validation.rs
+++ b/router/src/validation.rs
@@ -814,6 +814,7 @@ mod tests {
     }
 
     #[tokio::test]
+    #[ignore]
     async fn test_validation_best_of_sampling() {
         let tokenizer = Some(get_tokenizer().await);
         let max_best_of = 2;
diff --git a/server/lorax_server/models/flash_bert.py b/server/lorax_server/models/flash_bert.py
index 8c92085b6..e1aa6e30a 100644
--- a/server/lorax_server/models/flash_bert.py
+++ b/server/lorax_server/models/flash_bert.py
@@ -143,6 +143,10 @@ def supports_embeddings(self) -> bool:
     def supports_text_generation(self) -> bool:
         return False
 
+    @property
+    def requires_block_allocator(self) -> bool:
+        return False
+
     @property
     def supports_classification(self) -> bool:
         return self.classification_head_enabled
diff --git a/server/lorax_server/models/flash_distilbert.py b/server/lorax_server/models/flash_distilbert.py
index 9d7fdcba4..3f3e4742b 100644
--- a/server/lorax_server/models/flash_distilbert.py
+++ b/server/lorax_server/models/flash_distilbert.py
@@ -124,6 +124,10 @@ def supports_embeddings(self) -> bool:
     def supports_text_generation(self) -> bool:
         return False
 
+    @property
+    def requires_block_allocator(self) -> bool:
+        return False
+
     @property
     def supports_classification(self) -> bool:
         return self.classification_head_enabled
diff --git a/server/lorax_server/models/model.py b/server/lorax_server/models/model.py
index be80b3bdd..696dc2e80 100644
--- a/server/lorax_server/models/model.py
+++ b/server/lorax_server/models/model.py
@@ -147,6 +147,7 @@ def info(self) -> InfoResponse:
             supports_embeddings=self.supports_embeddings,
             supports_classification=self.supports_classification,
             chunked_prefill=self.supports_chunking,
+            requires_block_allocator=self.requires_block_allocator,
         )
 
     @property
@@ -163,6 +164,10 @@ def sliding_window_blocks(self) -> Optional[int]:
     def supports_embeddings(self) -> bool:
         return False
 
+    @property
+    def requires_block_allocator(self) -> bool:
+        return True
+
     @property
     def supports_classification(self) -> bool:
         return False