diff --git a/vllm/entrypoints/openai/completion/protocol.py b/vllm/entrypoints/openai/completion/protocol.py
index 6f8171f97b..1784d0f536 100644
--- a/vllm/entrypoints/openai/completion/protocol.py
+++ b/vllm/entrypoints/openai/completion/protocol.py
@@ -209,10 +209,10 @@ class CompletionRequest(OpenAIBaseModel):
         ),
     )
 
-    vllm_xargs: dict[str, str | int | float] | None = Field(
+    vllm_xargs: dict[str, str | int | float | list[str | int | float]] | None = Field(
         default=None,
         description=(
-            "Additional request parameters with string or "
+            "Additional request parameters with (list of) string or "
             "numeric values, used by custom extensions."
         ),
     )
diff --git a/vllm/entrypoints/speech_to_text/transcription/protocol.py b/vllm/entrypoints/speech_to_text/transcription/protocol.py
index abf1a11a0e..3d6600fe36 100644
--- a/vllm/entrypoints/speech_to_text/transcription/protocol.py
+++ b/vllm/entrypoints/speech_to_text/transcription/protocol.py
@@ -116,10 +116,10 @@ class TranscriptionRequest(OpenAIBaseModel):
     stream_include_usage: bool | None = False
     stream_continuous_usage_stats: bool | None = False
 
-    vllm_xargs: dict[str, str | int | float | bool] | None = Field(
+    vllm_xargs: dict[str, str | int | float | list[str | int | float]] | None = Field(
         default=None,
         description=(
-            "Additional request parameters with string or "
+            "Additional request parameters with (list of) string or "
             "numeric values, used by custom extensions."
         ),
     )