esp-runtime-mcp

list_serial_ports

Lists available serial ports and flags likely ESP devices (Espressif USB, CP210x, CH340/CH9102, FTDI bridges) so you can choose the correct port for ESP-IDF serial capture.

Instructions

List serial ports; likely_esp marks Espressif USB, CP210x, CH340/CH9102 and FTDI bridges.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "list_serial_ports"
  }
}

Input Schema

Name	Required	Description	Default
No arguments

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Oct 29, 2026

TDQS

A3.7/5.0

Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are provided, so the description carries the full behavioral burden. It does add genuine value by explaining the non-obvious `likely_esp` marker (which bridges count as Espressif), but it says nothing about enumeration behavior, whether ports can be busy/in use, or permissions.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

One sentence, zero waste, with the action front-loaded and the non-obvious field semantics appended. Nothing could be removed without losing information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a no-argument enumeration tool with an output schema present, this is nearly sufficient: the output schema covers the return shape and the description explains the one field whose meaning isn't self-evident. The only gap is the missing 'call this first to discover a port' workflow cue.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. The `likely_esp` note is arguably return-value semantics rather than parameter guidance.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

Specific verb+resource ('List serial ports') that an agent can immediately distinguish from the siblings, all of which operate on an already-selected port (capture_log, reset_device, read_coredump). It stops short of explicitly naming the sibling it precedes in the workflow, so it is clear but not differentiated in-text.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is only implied: the `likely_esp` explanation hints that this is how you pick an ESP device before calling capture_log or reset_device, but the description never states when to call this versus going straight to a capture, nor any prerequisites.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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