diff --git a/api-reference/asyncapi.yml b/api-reference/asyncapi.yml
index 1f4b5e9..6700ffd 100644
--- a/api-reference/asyncapi.yml
+++ b/api-reference/asyncapi.yml
@@ -72,6 +72,9 @@ channels:
       - `Authorization: Bearer <api_key>` - Required for authentication (see security section)
       - `model: <model_name>` - Optional; specifies which TTS model to use (see bindings). Falls back to `s2.1-pro` when omitted or unrecognized
 
+      ## Handshake
+      The WebSocket handshake must be performed over **HTTP/1.1**. HTTP/2 clients are rejected with `400 invalid protocol`, so disable HTTP/2 for the upgrade request (e.g. `curl --http1.1`).
+
 operations:
   receiveText:
     action: receive
diff --git a/api-reference/endpoint/openapi-v1/speech-to-text.mdx b/api-reference/endpoint/openapi-v1/speech-to-text.mdx
index 660a31a..dca1978 100644
--- a/api-reference/endpoint/openapi-v1/speech-to-text.mdx
+++ b/api-reference/endpoint/openapi-v1/speech-to-text.mdx
@@ -7,5 +7,5 @@ iconType: "solid"
 ---
 
 <Warning>
-This BETA endpoint only accepts `application/form-data` and `application/msgpack`.
+This BETA endpoint only accepts `multipart/form-data` and `application/msgpack`. It does not accept `application/json` (the audio field cannot be carried as JSON/base64).
 </Warning>