Cloud189 MCP server has well-structured tool definitions with consistent naming (verb_noun pattern: cloud189_*), complete input schemas with regex validation, and clear descriptions. However, output schemas are not documented, error handling lacks recovery guidance, and several tools lack parameter descriptions. 13/15 tools have descriptions (87%), but 6 tools have parameters without descriptions (40% of params undescribed). No tool annotations (readOnlyHint/destructiveHint) despite clear risk stratification. Schemas are present and typed but output structure is undocumented.

• Add output schema documentation to every tool. Document the JSON structure returned by cloud189_status, cloud189_list, cloud189_tree, etc. Include field names, types, and what each field represents. This enables LLMs to extract the right data for downstream calls.
• Implement tool annotations. Add destructiveHint: true to cloud189_rm and cloud189_mv. Add idempotentHint: true to cloud189_upload_safe and cloud189_mkdir_safe (reuse existing folders). Add readOnlyHint: true to all query tools (cloud189_list, cloud189_search, cloud189_quota). This signals safety properties to LLMs without requiring them to parse descriptions.
• Enhance error messages with recovery guidance. When a folder ID is invalid, return: 'Invalid folder ID. Call cloud189_list() to discover valid folder IDs.' When confirm=false, return: 'Confirmation required. Retry with confirm=true to execute.' This guides LLMs to self-correct.
• Add descriptions to all optional parameters. Clarify 'dir' in cloud189_download, cloud189_rm, cloud189_mv: 'Set to true if the remote ID refers to a folder; false for files.' Clarify 'name' and 'parent' in cloud189_rm and cloud189_mv: 'Optional. Used for audit logging. Improves error messages if the operation fails.'
• Document pagination and result limits. cloud189_list and cloud189_tree should state: 'Returns up to 100 items per call. For larger folders, use cloud189_search() with a keyword filter or call cloud189_tree() with depth limit.' This prevents context window exhaustion.