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ESP32 serial port tool — minimal stdio MCP server for device communication, chip identification, and log capture. Zero dependencies except pyserial.
Four tools with complete schemas and descriptions, but significant gaps in parameter documentation and error guidance. Tool names follow verb_noun pattern (esp32_list_devices, esp32_chip_id, esp32_capture, esp32_reset). Descriptions are present (avg 150 chars) but lack actionable context for LLM selection. Input schemas are properly typed JSON Schema objects. Critical issue: parameters lack descriptions in schema definitions (port, seconds, reset, esptool_reset have no 'description' field in inputSchema). Error handling returns raw exception messages rather than recovery guidance. No output schema documented. Composition is sound, each tool has one responsibility.
Capture serial output for N seconds (boot log / runtime logs). By default resets the board into app mode first so a fresh boot log is captured. Use esptool_reset=true to recover a frozen (hung loop) board.
Identify the connected ESP32 chip (ESP32-S3 vs ESP32-C3) via esptool. Ends by hard-resetting the board into app mode.
List USB serial devices on this Mac (ESP32 usage boards appear as /dev/cu.usbmodem*).
Hard-reset the board into app mode via DTR/RTS pulse (recover from a hung/frozen loop).
Parameter descriptions missing in inputSchema. 'port', 'seconds', 'reset', 'esptool_reset' have no 'description' field in the JSON Schema objects, violating pattern:tool-description. LLMs cannot infer parameter meaning from names alone.
No output schema documented. Tool responses return unstructured text (e.g., 'No serial output in 20s on /dev/cu.usbmodem0'). LLMs cannot plan downstream calls or extract structured data. Violates pattern:response-shaper.
Error handling returns raw exception messages ('esptool chip_id timed out on /dev/cu.usbmodem0') without recovery guidance. Violates pattern:recovery-guide. Should suggest 'Retry with a longer timeout' or 'Check if device is in download mode'.
| Scored | Grade | Overall | Spec posture | Rubric |
|---|---|---|---|---|
| 2026-09-23 | D | 50 | 2026-07-28+ | v2 |
Tool descriptions lack WHEN-to-use context. 'esp32_capture' description does not explain when to use reset=true vs esptool_reset=true, or when to call esp32_reset separately. LLMs cannot disambiguate tool selection.
No tool annotations (readOnlyHint, destructiveHint, idempotentHint). esp32_chip_id and esp32_capture perform hardware resets (destructive side effects) but are not marked. Violates current spec alignment for tool annotations.