Otii MCP server

An MCP server that lets AI assistants measure the energy consumption of your device with a Qoitech Otii Arc or Otii Ace. You can ask your assistant things like:

Power my board at 3.3 V for 20 seconds and tell me how much energy one cycle uses.

I changed the firmware to sleep between transmissions, measure again and compare with the previous recording.

The server powers your device under test from the Otii, records current and (optionally) the device's UART log, and computes energy, charge and current statistics. These can cover a whole recording, a time range, or the interval between two log messages.

Early preview. Tool names and parameters may change. Feedback is welcome through GitHub issues.

Requirements

• An Otii Arc or Otii Ace connected to your computer.

• The Otii 3 desktop application running, with its TCP server enabled.

• An Otii account with an Automation license available. The server reserves one license for each tool call and returns it afterwards.

• uv, used to run the server without a manual install.

Related MCP server: arduino-mcp-server

Configuration

The server is configured through environment variables, set in your MCP client's configuration:

If the Otii application is already logged in, no credentials are needed.

A credentials file keeps your password out of the MCP client's configuration:

{
  "username": "your-otii-account@example.com",
  "password": "your-otii-password"
}

Adding the server to your MCP client

Claude Code

claude mcp add otii --env OTII_CREDENTIALS=$HOME/.config/otii/credentials.json \
  -- uvx --from git+https://github.com/qoitech/otii-mcp otii-mcp

Add --scope project to write it to the repository's .mcp.json, so that everyone working on the firmware gets it.

Claude Desktop, Cursor, VS Code and other clients

Most clients use the same JSON format: claude_desktop_config.json for Claude Desktop, .cursor/mcp.json for Cursor, and .vscode/mcp.json (under "servers") for VS Code.

{
  "mcpServers": {
    "otii": {
      "command": "uvx",
      "args": ["--from", "git+https://github.com/qoitech/otii-mcp", "otii-mcp"],
      "env": {
        "OTII_CREDENTIALS": "/path/to/credentials.json"
      }
    }
  }
}

From a local clone

git clone https://github.com/qoitech/otii-mcp

Then use "command": "uv" with "args": ["run", "--directory", "/path/to/otii-mcp", "otii-mcp"].

Tools

Recordings are stored in the project that is open in the Otii application, so you can open them there for a closer look.

Measuring per-cycle energy with UART log markers

The most useful measurements come from combining the current with your firmware's log output:

1. Connect the device's UART TX to the Otii RX, and set exp_voltage to the device's IO voltage.

2. Make your firmware print a fixed line once per cycle, e.g. Connecting....

3. Ask the assistant to measure with uart_baudrate set. It then calls energy_between_messages with that line to get the energy of one cycle. occurrence: 1 skips the first cycle, which includes boot.

Tip: if your device is also connected over USB for flashing or debugging, it may be partly powered from USB, which makes the measurements wrong. Use set_gpo to switch a USB power switch off while measuring.

Safety

measure turns on the Otii main output at the voltage you, or the assistant, choose. Tell the assistant your device's supply voltage, and set max_current_A to a sensible limit. Consider allowing measure, set_gpo and set_ace_0_15_voltage only after confirmation in your MCP client.

License

MIT