Arduino MCP has 20 tools with complete schemas and descriptions, but quality is inconsistent. Tool names follow verb_noun convention (list_ports, compile_sketch, upload_sketch). Most descriptions are present but generic (10-50 chars for many tools). Parameter descriptions exist but lack constraints, ranges, and format specifications. No output schemas documented. Error handling is minimal, most tools return raw CLI output or generic errors without recovery guidance. The image_to_c_array tool has 11 parameters but lacks enum constraints for format_type, orientation, and rotation despite having fixed valid values. Serial tools (read_serial, write_serial, monitor_serial) lack timeout/retry guidance. No pagination support despite tools that could return large lists (search, list_installed_libraries). Tool composition is reasonable but some tools combine multiple concerns (e.g., arduino_cli_command is a raw passthrough that bypasses safety).

• Document output schemas for all tools. Specify field names, types, and whether fields are always present. Example: list_ports returns [{port: string, description: string, hardware_id: string}].
• Add enum constraints to image_to_c_array parameters: format_type: enum[monochrome, grayscale_2bit, grayscale_4bit, grayscale, rgb565, rgb888], orientation: enum[horizontal, vertical], rotation: enum[0, 90, 180, 270].
• Enhance serial tool descriptions with timeout and error recovery guidance. Example: 'If timeout occurs, the port may be busy. Verify no other process is using it, then retry.'
• Implement pagination for search tool: add limit (default 20, max 100) and offset parameters. Return total_count and next_offset in response.
• Restrict arduino_cli_command to a whitelist of safe subcommands (board, lib, core list/search/info) and reject destructive commands (uninstall, remove). Alternatively, add a --dry-run flag and require explicit confirmation for write operations.