This MCP server exposes 6 Google Drive tools with reasonably well-structured Zod schemas and descriptions. Most tools follow verb-noun naming conventions (g_drive_list_files_by_type, g_drive_search_files, g_drive_read_file, etc.). Schemas are present and typed for all tools with Zod validators. However, there are significant gaps: (1) Output schemas are not documented, the code returns createSuccessResponse() and createErrorResponse() wrappers, but the actual response structure is not declared in tool metadata, forcing LLMs to infer outputs. (2) Parameter descriptions, while present, are sometimes vague or lack constraint details, e.g., 'maxResults' has no bounds stated ('default: 50, max: 100' appears in text but not as min/max schema constraints). (3) Error handling is basic, most tools catch errors generically and return Japanese error messages without guidance on recovery or retry strategy. (4) The g_drive_insert_value tool is overloaded with conditional logic for three different file types (docs, sheets, presentations), making it harder for LLMs to reason about side effects. (5) No tool annotations (readOnlyHint, destructiveHint) are present to signal which tools modify state vs. read-only. Tool #6 (g_drive_insert_value) is marked WRITE but has no annotation to signal this to the MCP client.

• Document output schemas for all 6 tools. For example, g_drive_list_files_by_type should declare: returns {status: string, fileType: string, totalCount: number, files: Array<{id: string, name: string, webViewLink: string, ...}>}. Use TypeScript interface exports or JSDoc @returns blocks visible in tool metadata.
• Add tool annotations to all tool registrations: server.tool(..., { annotations: { readOnlyHint: true } }) for read-only tools (g_drive_list_files_by_type, g_drive_search_files, g_drive_read_file, g_drive_get_comments, g_drive_read_file_part) and { annotations: { destructiveHint: true } } for g_drive_insert_value.
• Split g_drive_insert_value into three separate tools: insert_into_google_doc, insert_into_google_sheet, insert_into_google_slide. Each has a focused parameter set and clear behavior. This matches the single-responsibility principle and enables LLMs to reason about preconditions accurately.
• Enforce parameter constraints in Zod schemas using .max(), .min(), .regex() instead of documenting them in description text only. For example, z.number().min(1).max(100).default(50) for maxResults. LLMs parse schema constraints; they often ignore description prose.
• Document parameter interdependencies explicitly. For g_drive_read_file_part, update the fileType description to say: 'If fileType=docs, provide tabId; if fileType=sheets, provide range; if fileType=presentations, provide pageNumber. Only one of these is valid per call.'
• Replace generic error messages with error classification and recovery hints. For example, if fileId is invalid, return {status: 'error', code: 'FILE_NOT_FOUND', message: 'File ID abc123 does not exist or is not accessible. Try search_files() to find the correct file ID.', retryable: false}. This tells LLMs when to retry vs. when to ask the user.