docs(agentkit): align OpenAI TTS instructions support

Author: digitallysavvy

changelog.md

@@ -107,7 +107,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/).
 
 ### Added
 
-- **`OpenAITTS`** — New optional parameters: `response_format` (str, e.g. `"pcm"`) and `speed` (float).
+- **`OpenAITTS`** — New optional parameters: `instructions` (str) and `speed` (float).
 - **`CartesiaTTS`** — `voice_id` user-facing field is preserved; voice is serialized to the required nested object format automatically.
 - **`RimeTTS`** — New optional parameters: `lang` (str), `sampling_rate` (int, serialized as `samplingRate`), `speed_alpha` (float, serialized as `speedAlpha`).
 - **`OpenAIRealtime`** — New optional parameter: `failure_message` (str).

docs/reference/vendors.md

@@ -190,6 +190,7 @@ The SDK also includes named helpers for the remaining Agora-supported LLM provid
 | `voice` | `str` | Yes | — | Voice: `alloy`, `echo`, `fable`, `onyx`, `nova`, `shimmer` |
 | `model` | `str` | BYOK only | `None` | Model: `tts-1` or `tts-1-hd` |
 | `base_url` | `str` | BYOK only | `None` | OpenAI TTS endpoint URL |
+| `instructions` | `str` | No | `None` | Custom instructions for voice style, accent, pace, and tone |
 | `speed` | `float` | No | `None` | Speech speed multiplier |
 | `skip_patterns` | `List[int]` | No | `None` | Skip patterns |
 

tests/custom/test_tts_vendors.py

@@ -52,11 +52,12 @@ def test_tts_vendor_params_match_generated_core_shapes() -> None:
         "encoding": "linear16",
     }
 
-    assert OpenAITTS(api_key="openai-key", voice="coral", model="gpt-4o-mini-tts", base_url="https://api.openai.com/v1").to_config()["params"] == {
+    assert OpenAITTS(api_key="openai-key", voice="coral", model="gpt-4o-mini-tts", base_url="https://api.openai.com/v1", instructions="speak clearly").to_config()["params"] == {
         "voice": "coral",
         "api_key": "openai-key",
         "base_url": "https://api.openai.com/v1",
         "model": "gpt-4o-mini-tts",
+        "instructions": "speak clearly",
     }
 
     assert OpenAITTS(voice="coral").to_config()["params"] == {