YouTube Tools MCP has clear, action-verb naming (get_*, list_, search_) and reasonable descriptions (avg ~80 chars). All 7 tools have input schemas with type definitions and parameter descriptions. However, output schemas are not documented in the visible code, parameter descriptions lack detail on constraints/formats, and error handling guidance is minimal. No tool annotations (readOnlyHint, etc.) despite all being read-only. Schemas are present but sparse, most parameters lack min/max bounds, enums, or format specifications. This is a solid C+ server: functional definitions, but missing production-grade polish.

• Document output schemas for all 7 tools. Specify return type (object/array), field names, types, and descriptions. Example: get_youtube_video_info returns {videoId: string, title: string, views: number, duration: number, ...}.
• Add enums and bounds to parameters. Change 'language' to enum: ['en', 'vi', 'es', ...]; add 'limit' constraints: minimum 1, maximum 100, default 15.
• Add readOnlyHint: true to all tool definitions in src/mcp.ts. This signals to agents that these tools are safe to call without side effects.
• Enhance error descriptions with recovery paths. E.g., 'If video_id is invalid, try search_youtube_videos() first to find the correct ID.'
• Add pagination guidance to get_youtube_channel_videos and search_youtube_videos. Document default limits (15, 10) and explain how to fetch more results.