R-Server MCP has significant definition quality gaps. Tool names lack clear action verbs (mount_directory, render_ggplot are acceptable but execute_r_script is vague). Descriptions are present but generic (10-50 chars for most). Parameter descriptions exist but lack constraints, ranges, and format guidance. No output schemas documented. Error handling is minimal, tools return dicts with 'success' flags but no recovery guidance. Security concerns: execute_r_script accepts arbitrary R code with no validation or sandboxing hints. The server exposes file system operations (mount_directory, upload_file) without clear permission boundaries or audit trails.

• Add output schema documentation for each tool. Example for render_ggplot: 'Returns {image_base64: string, format: string, width: int, height: int, execution_time_ms: int}'.
• Add parameter constraints to descriptions. E.g., 'r_code (string, max 50KB, timeout 30s, no system() or file.remove() calls)' and 'width (integer, 100-4000 pixels, default 800)'.
• Implement input validation with actionable error messages. E.g., 'Invalid output_format: got "bmp", must be one of: png, jpeg, pdf, svg'.
• Add permission checks and audit logging to mount_directory and upload_file. Log caller, timestamp, path, and operation result to stderr or a log file.
• Wrap execute_r_script in a sandbox or timeout guard. Return structured errors: {success: false, error_type: 'timeout|syntax|permission|runtime', message: '...', recovery_hint: '...'}