Meshtastic MCP Server

An MCP server for working with the Meshtastic firmware repo and connected devices. Lets Claude Code / Claude Desktop:

• Discover USB-connected Meshtastic devices
• Enumerate PlatformIO board variants (166+) with Meshtastic metadata
• Build, clean, flash, erase-and-flash (factory), and OTA-update firmware
• Read serial logs via pio device monitor (with board-specific exception decoders)
• Trigger 1200bps touch-reset for bootloader entry (nRF52, ESP32-S3, RP2040)
• Query and administer a running node via the meshtastic Python API: owner name, config (LocalConfig + ModuleConfig), channels, messaging, reboot/shutdown/factory-reset
• Call esptool, nrfutil, picotool directly when PlatformIO doesn't cover the operation

Design principle

PlatformIO first. Its pio run -t upload knows the correct protocol, offsets, and post-build chain for every variant in variants/. Direct vendor-tool wrappers (esptool_*, nrfutil_*, picotool_*) exist as escape hatches for operations pio doesn't cover (blank-chip erase, DFU .zip packages, BOOTSEL-mode inspection).

Prerequisites

• Python ≥ 3.11
• PlatformIO Core — pio on $PATH or at ~/.platformio/penv/bin/pio
• The Meshtastic firmware repo checked out somewhere (set via MESHTASTIC_FIRMWARE_ROOT)
• Optional: esptool, nrfutil, picotool on $PATH (or under the firmware venv at .venv/bin/) if you want to use the direct-tool wrappers

Install

cd <firmware-repo>/mcp-server
python3 -m venv .venv
.venv/bin/pip install -e .

Verify:

MESHTASTIC_FIRMWARE_ROOT=<firmware-repo> .venv/bin/python -m meshtastic_mcp

The server blocks on stdin (that's correct — it speaks MCP over stdio). Ctrl-C to exit.

Register with Claude Code

Edit ~/.claude/settings.json (global) or <firmware-repo>/.claude/settings.local.json (project-only):

{
  "mcpServers": {
    "meshtastic": {
      "command": "<firmware-repo>/mcp-server/.venv/bin/python",
      "args": ["-m", "meshtastic_mcp"],
      "env": {
        "MESHTASTIC_FIRMWARE_ROOT": "<firmware-repo>"
      }
    }
  }
}

Replace <firmware-repo> with the absolute path, e.g. /Users/you/GitHub/firmware. Restart Claude Code after editing.

Register with Claude Desktop

Same mcpServers block, but in ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows).

Tools (43)

Discovery & metadata

Build & flash

Serial log sessions

Backed by long-running pio device monitor subprocesses with a 10k-line ring buffer per session and board-specific filters (esp32_exception_decoder auto-selected when you pass env=).

Device reads

The tool tables below document 38 currently registered MCP server tools.

Device writes

Direct hardware tools (escape hatches)

USB power control (uhubctl)

Target a port by explicit (location, port) (raw uhubctl syntax like location="1-1.3", port=2) or by role ("nrf52", "esp32s3"). Role lookup checks MESHTASTIC_UHUBCTL_LOCATION_<ROLE> + MESHTASTIC_UHUBCTL_PORT_<ROLE> env vars first, then auto-detects via VID against uhubctl's output.

Requires uhubctl on PATH:

brew install uhubctl        # macOS
apt install uhubctl         # Debian/Ubuntu

Modern macOS + PPPS-capable hubs generally work without root. On Linux without udev rules, or on old macOS with driver quirks, you may need sudo. If uhubctl returns a permission error the MCP tool raises a clear UhubctlError pointing at the udev-rules / sudo fallback rather than auto-sudo'ing mid-run.

Safety

• All destructive flash/admin tools require confirm=True as a tool-level gate, on top of any permission prompt from Claude.
• Serial port is exclusive. If a serial_* session is active on a port, device_info/admin tools on the same port will fail fast with a pointer at the active session_id. Close the session first.
• Flash confirmation by architecture: erase_and_flash / update_flash error if the env's architecture isn't ESP32 — use pio_flash for nRF52/RP2040/STM32.

Environment variables

TCP / native-host nodes

The native-macos and native PlatformIO envs build a headless meshtasticd binary that runs on the host (Apple Silicon / Intel macOS, or Linux Portduino). The daemon exposes the meshtastic TCP API on port 4403 rather than a USB serial endpoint — point the MCP server at it via MESHTASTIC_MCP_TCP_HOST:

# 1. Build + run a daemon on this host (see variants/native/portduino/platformio.ini
#    for full Homebrew prereqs and CH341 LoRa-adapter setup).
pio run -e native-macos
~/.meshtasticd/meshtasticd

# 2. Point the MCP server at it.
export MESHTASTIC_MCP_TCP_HOST=localhost     # or host:port, default port 4403

First-run gotcha — MAC address. meshtasticd derives its MAC from the USB adapter's serial-number / product strings. Many cheap CH341 dongles (MeshStick included — VID 0x1A86 / PID 0x5512) ship with iSerialNumber=0 and iProduct=0, so the daemon aborts on boot with *** Blank MAC Address not allowed!. Set the MAC explicitly in config.yaml:

# Under General:
MACAddress: 02:CA:FE:BA:BE:01

Use a locally-administered address (first byte's second-LSB set, e.g. 02:* / 06:* / 0A:* / 0E:*) to avoid colliding with a real OUI.

There is also a --hwid AA:BB:CC:DD:EE:FF CLI flag visible in meshtasticd --help, but it is currently broken in MAC_from_string() (src/platform/portduino/PortduinoGlue.cpp): the function strips colons from its parameter but then reads bytes from the global portduino_config.mac_address, so --hwid is silently overridden when MACAddress: is also set, and crashes the daemon (uncaught std::invalid_argument: stoi: no conversion) when it isn't. Use the YAML form until that's fixed upstream.

list_devices will surface the daemon as tcp://localhost:4403 with likely_meshtastic=True, so device_info, list_nodes, get_config, set_config, set_owner, send_text, userprefs_*, and the admin RPCs auto-select it when no port is passed. Pass port="tcp://other-host:9999" explicitly to target a different daemon.

Tools that don't apply to a TCP/native node (no USB hardware to operate on) raise a clear ConnectionError rather than failing mysteriously: pio_flash, erase_and_flash, update_flash, touch_1200bps, serial_open (use info/admin tools directly), and the vendor escape hatches esptool_*, nrfutil_*, picotool_*. pio_flash against a native* env similarly raises — there's no upload step; use build and run the binary directly.

The pytest harness in tests/ still assumes USB-attached devices per role — TCP-aware fixtures are not part of this surface yet.

Hardware Test Suite

mcp-server/tests/ holds a pytest-based integration suite that exercises real USB-connected Meshtastic devices against the MCP server surface. Separate from the native C++ unit tests in the firmware repo's top-level test/ directory — this one validates the device-facing behavior end-to-end.

Invocation

./mcp-server/run-tests.sh                               # full suite (auto-detect + auto-bake-if-needed)
./mcp-server/run-tests.sh --force-bake                  # reflash devices before testing
./mcp-server/run-tests.sh --assume-baked                # skip the bake step (caller vouches for state)
./mcp-server/run-tests.sh tests/mesh                    # one tier
./mcp-server/run-tests.sh tests/mesh/test_traceroute.py # one file
./mcp-server/run-tests.sh -k telemetry                  # pytest name filter

The wrapper auto-detects connected devices (VID 0x239A → nrf52 → env rak4631; 0x303A or 0x10C4 → esp32s3 → env heltec-v3), exports MESHTASTIC_MCP_ENV_<ROLE> env vars, and invokes pytest. Overrides via per-role env vars: MESHTASTIC_MCP_ENV_NRF52=heltec-mesh-node-t114 ./run-tests.sh.

No hardware connected? The wrapper narrows to tests/unit/ only and says so in the pre-flight header.

Tiers (run in this order)

• bake (tests/test_00_bake.py) — flashes both hub roles with the session's test profile. Has a skip-if-already-baked check (region + channel match); --force-bake overrides.
• unit — pure Python, no hardware. boards / PIO wrapper / userPrefs-parse / testing-profile fixtures.
• mesh — 2-device mesh: formation, broadcast delivery, direct+ACK, traceroute, bidirectional. Parametrized over both directions. Includes test_peer_offline_recovery which uses uhubctl to power-cycle one peer mid-conversation and verifies the mesh recovers (skips without uhubctl).
• telemetry — periodic telemetry broadcast + on-demand request/reply (TELEMETRY_APP with wantResponse=True).
• monitor — boot log has no panic markers within 60 s of reboot.
• recovery — uhubctl power-cycle round-trip: verifies the hub port can be toggled off/on, the device re-enumerates with the same my_node_num, and NVS-resident config (region, channel, modem preset) survives a hard reset. Requires uhubctl on PATH; skips cleanly otherwise.
• ui — input-broker-driven screen navigation (AdminMessage.send_input_event injection → Screen::handleInputEvent → frame transition). Parametrized on the screen-bearing role (heltec-v3 OLED). Captures images via USB webcam + OCRs them for HTML-report evidence. Requires pip install -e '.[ui]' and MESHTASTIC_UI_CAMERA_DEVICE_ESP32S3=<index>; tier is auto-deselected if cv2 isn't importable.
• fleet — PSK-seed isolation: two labs with different seeds never overlap.
• admin — owner persistence across reboot, channel URL round-trip, lora.hop_limit persistence.
• provisioning — region/channel baking, userPrefs survive factory_reset(full=False).

UI tier setup

The tests/ui/ tier drives the on-device OLED via the firmware's existing AdminMessage.send_input_event RPC (no firmware changes required) and verifies transitions via a macro-gated log line + camera + OCR. Summary:

1. Install extras: pip install -e 'mcp-server/.[ui]' — pulls in opencv-python-headless, numpy, easyocr, Pillow. First easyocr run downloads ~100 MB of models to ~/.EasyOCR/; an autouse session fixture pre-warms the reader so per-test OCR is <100 ms after that.
2. Point a USB webcam at the heltec-v3 OLED. Discover its index:
   bashCopy

   .venv/bin/python -c "import cv2; [print(i, cv2.VideoCapture(i).read()[0]) for i in range(5)]"
   

3. Export the per-role device env var:
   bashCopy

   export MESHTASTIC_UI_CAMERA_DEVICE_ESP32S3=0
   

4. Run:
   bashCopy

   ./run-tests.sh tests/ui -v
   

   Captures land under tests/ui_captures/<session_seed>/<test_id>/, one PNG + .ocr.txt per frame_capture() call, with a per-test transcript.md stepping through event → frame → OCR. The HTML report embeds the full image strip inline (pass or fail).

On macOS, cv2.VideoCapture(0) triggers the TCC Camera permission prompt on first use. Pre-grant Terminal (or your IDE's terminal) before running. The OpenCVBackend fails fast on 10 consecutive black frames so a silent permission denial surfaces as a clear error, not an empty PNG strip.

No camera? Set MESHTASTIC_UI_CAMERA_BACKEND=null (or leave the device var unset). Tests still exercise the event-injection path and log assertions; captures just become 1×1 black PNGs.

Artifacts (regenerated every run, under tests/)

• report.html — self-contained pytest-html report. Each test gets a Meshtastic debug section attached on failure with a 200-line firmware log tail + device-state dump. Open this first on failures.
• junit.xml — CI-parseable.
• reportlog.jsonl — pytest-reportlog event stream; consumed by the TUI.
• fwlog.jsonl — firmware log mirror (meshtastic.log.line pubsub → JSONL).
• flash.log — tee of all pio / esptool / nrfutil / picotool subprocess output during the run (driven by MESHTASTIC_MCP_FLASH_LOG).

Live TUI

.venv/bin/meshtastic-mcp-test-tui
.venv/bin/meshtastic-mcp-test-tui tests/mesh    # pytest args pass through

Textual-based wrapper over run-tests.sh with a live test tree, tier counters, pytest output pane, firmware-log pane, and a device-status strip. Key bindings: r re-run focused, f filter, d failure detail, g open report.html, x export reproducer bundle, l cycle fw-log filter, q quit (SIGINT → SIGTERM → SIGKILL escalation).

Set MESHTASTIC_UI_TUI_CAMERA=1 to mount a bottom-of-screen UI camera panel. Left side: the latest capture PNG rendered as Unicode half-blocks (via rich-pixels, works in any terminal — no kitty/sixel required). Right side: live transcript tail ("step 3 — frame 4/8 name=nodelist_nodes — OCR: Nodes 2/2") so you can see every event-injection and its result as each UI test runs. Requires the [ui] extras for image rendering; the transcript alone works without them.

Slash commands

Three AI-assisted workflows are wired up for Claude Code operators (.claude/commands/) and Copilot operators (.github/prompts/): /test (run + interpret), /diagnose (read-only health report), /repro (flake triage, N-times re-run with log diff).

House rules (for human + agent contributors)

• Session-scoped fixtures in tests/conftest.py snapshot + restore userPrefs.jsonc; never edit userPrefs.jsonc from inside a test. Use the test_profile / no_region_profile fixtures for ephemeral overrides.
• SerialInterface holds an exclusive port lock; sequence calls open → mutate → close, then next device. No parallel calls to the same port.
• Directed PKI-encrypted sends need bilateral NodeInfo warmup — both sides must hold the other's current pubkey. See tests/mesh/_receive.py::nudge_nodeinfo_port and the three directed- send tests (test_direct_with_ack, test_traceroute, test_telemetry_request_reply) for the canonical pattern.

Layout

mcp-server/
├── pyproject.toml
├── README.md
└── src/meshtastic_mcp/
    ├── __main__.py         # entry: python -m meshtastic_mcp
    ├── server.py           # FastMCP app + @app.tool() registrations (thin)
    ├── config.py           # firmware_root, pio_bin, esptool_bin, etc.
    ├── pio.py              # subprocess wrapper (timeouts, JSON, tail_lines)
    ├── devices.py          # list_devices (findPorts + comports)
    ├── boards.py           # list_boards / get_board (pio project config parse + cache)
    ├── flash.py            # build, clean, flash, erase_and_flash, update_flash, touch_1200bps
    ├── serial_session.py   # SerialSession + reader thread + ring buffer
    ├── registry.py         # session registry + per-port locks
    ├── connection.py       # connect(port) ctx mgr — SerialInterface + port lock
    ├── info.py             # device_info, list_nodes
    ├── admin.py            # set_owner, get/set_config, channels, send_text, reboot/shutdown/factory_reset
    └── hw_tools.py         # esptool / nrfutil / picotool wrappers

Troubleshooting

• "Could not locate Meshtastic firmware root" — set MESHTASTIC_FIRMWARE_ROOT.
• "Could not find pio" — install PlatformIO or set MESHTASTIC_PIO_BIN.
• "Port is held by serial session ..." — call serial_close(session_id) or serial_list to find it.
• factory.bin not found after build — the env may not be ESP32; only ESP32 envs produce a .factory.bin.
• touch_1200bps reported new_port: null — the device may not have 1200bps-reset stdio, or the bootloader re-uses the same port name. Check list_devices manually.