gallo-mcp

A Model Context Protocol (MCP) server that exposes a Pico de Gallo USB bridge to AI coding agents. It wraps pico-de-gallo-lib and presents one MCP tool per peripheral operation (I²C, SPI, UART, GPIO, PWM, ADC, 1-Wire) over stdio, so an agent can probe and drive real hardware while writing an embedded driver.

Install

cargo install gallo-mcp

Run

gallo-mcp [--serial-number <SN>]

The server holds no persistent connection to the board. Each tool call opens the device, runs the operation, and releases it when the call completes, so the board stays free for the gallo CLI or other host processes between calls. Each call re-opens and re-validates the device, so there is a small fixed per-call connection cost. The server starts even with no board attached; tools begin working as soon as a Pico de Gallo is plugged in. Logs go to stderr; stdout carries the MCP protocol.

Use with an MCP client

Add it to your client's MCP configuration. For example, opencode (opencode.json, safe to commit per-project):

{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "pico-de-gallo": { "type": "local", "command": ["gallo-mcp"], "enabled": true }
  }
}

Security

Tools that write to a bus or actuate pins are annotated destructiveHint; read-only tools are annotated readOnlyHint. gallo-mcp does not gate writes itself — approval is delegated to the MCP client. Configure your client's permission system (e.g. opencode permission) to prompt before destructive tool calls. Under a client with no permission system, an agent can actuate hardware without confirmation.

See the book chapter for the full tool catalog and details.