Single tool with basic definition. Tool name 'use_voice' lacks action verb clarity (should be 'speak' or 'play_voice'). Description is present (139 chars) and somewhat actionable but includes unhelpful instruction text ('ONLY USE IF ASKED') that should be agent behavior, not tool documentation. Input schema is properly typed (string) with description (52 chars). No output schema documented, return value is a simple duration string, not a structured object. No error handling, validation, or recovery guidance. No parameter constraints (e.g., max text length, language support). Tool performs READ_ONLY operation but lacks proper risk classification. No composition considerations (tool is isolated, no chaining IDs). Overall, this is a bare-minimum implementation suitable only for simple voice playback, not production agent integration.

• Rename tool to 'speak' or 'generate_speech', start with action verb to signal intent clearly.
• Document output schema: {"status": "success"|"error", "duration_seconds": number, "message": string}. This allows LLMs to understand and chain results.
• Remove agent behavior instructions from description. Replace with: 'Generate spoken audio from text using Piper TTS. Returns duration and success status. Requires piper binary, sox, and audio device.'
• Add input validation: constrain 'text' parameter to max 1000 chars, validate UTF-8 encoding, reject control characters.
• Wrap subprocess calls in try-catch. Return structured error response: {"status": "error", "code": "piper_not_found"|"audio_device_failed"|"timeout", "message": "...", "recovery": "..."} with actionable recovery hints.
• Document tool prerequisites in description: 'Requires: piper binary in scripts/, sox installed, audio device accessible.'
• Add timeout parameter (default 30s) to prevent hung subprocess blocks.
• Consider adding 'voice_id' or 'language' parameter if piper supports multiple voices, currently hardcoded to 'en_US-amy-medium'.