Server provides 4 well-named, action-verb tools (assess_, transcribe_, synthesize_, list_) with clear docstrings and complete input schemas. All parameters have type annotations and descriptions. However, output schemas are not documented, responses are returned as raw dicts without field documentation, forcing LLMs to infer structure. Parameter descriptions lack constraint details (e.g., audio format specifics, speed range 0.5-2.0 is mentioned but not validated). No error handling guidance or recovery paths documented. Tool descriptions are adequate (100-200 chars) but could better explain when to use each tool vs. alternatives.

• Document output schemas for all tools. E.g., assess_pronunciation returns {overall_score: int, word_scores: [{word: str, score: int}], phoneme_feedback: [...]}. Include field types and descriptions.
• Add enum constraints for language codes (e.g., language: Literal['en-US', 'pt-BR', 'es-ES', ...]) and validate voice parameter against list_voices output.
• Wrap API calls in try-except blocks. Return structured error responses: {error: str, code: str, recovery_hint: str}. E.g., 'Invalid audio format. Supported: WAV, MP3, WEBM, OGG.'
• Add parameter validation with clear error messages. Validate speed in [0.5, 2.0], audio_base64 is valid base64, language is a known code.
• Document tool relationships and discovery flow. E.g., 'Call list_voices first to see available options before calling synthesize_speech.'