systemlink-mcp

An MCP server that exposes NI SystemLink to AI clients with test-and-measurement-native tools: yield by product revision, failing DUT steps versus spec limits, measurement-trace summaries, and calibration-due assets.

This is the fleet/data-layer companion to daq-mcp. daq-mcp talks to a single DAQ device. systemlink-mcp queries and correlates results, assets, and systems across a lab.

This is a personal project with one maintainer. It is not an NI product and is not affiliated with, endorsed by, or supported by NI / Emerson.

Why test-domain tools instead of a generic wrapper

A commercial middleware catalog can list SystemLink among thousands of industrial systems and then expose a CMMS/ERP-shaped surface: work orders, sites, spaces, sales orders. That abstraction cannot answer what a test engineer actually asks:

• pass/fail rates for product revision B this quarter
• which measurement on a failing DUT exceeded its limit
• which PXI module is past its calibration due date

Every tool here is shaped around those questions. Responses are summaries plus a bounded preview, not raw Test Monitor or DataFrame payloads. Dumping thousands of result rows or a 2000-point waveform into a model context makes the server unusable even if the API calls are correct.

Read-only by default

Mutating tools (update_result_properties, execute_notebook) refuse unless SYSTEMLINK_MCP_ALLOW_WRITE=1. Read tools work with no extra flags.

The current nisystemlink-clients AssetManagementClient has create, query, delete, file-link, and utilization methods, but no asset update method. The gated write surface therefore updates Test Monitor result metadata and queues notebook executions, not asset records.

Stack

Python 3.11+, uv, FastMCP (stdio or Streamable HTTP), Pydantic v2, and the official nisystemlink-clients package. Tools never import the SDK; they call a SystemLinkBackend. Set SYSTEMLINK_MCP_SIMULATE=1 for a pure-Python fake that needs no SystemLink server.

Quick start (no SystemLink server)

uv sync
SYSTEMLINK_MCP_SIMULATE=1 uv run server.py

PowerShell:

$env:SYSTEMLINK_MCP_SIMULATE="1"; uv run server.py

Real SystemLink

The simulated backend is only used when SYSTEMLINK_MCP_SIMULATE=1, or when a live connect fails and SYSTEMLINK_MCP_REQUIRE_REAL is unset. A live response has "backend": "systemlink" and "simulated": false.

1. Create an API key in SystemLink (Enterprise: a policy, then an API key; the HTTP header the SDK sends is x-ni-api-key). SLE does not accept username and password for programmatic access.
2. Copy .env.example to .env (gitignored) and set:

SYSTEMLINK_SERVER_URI=https://your-systemlink-host
SYSTEMLINK_API_KEY=...
SYSTEMLINK_MCP_REQUIRE_REAL=1

Leave SYSTEMLINK_MCP_SIMULATE unset. On-prem SystemLink Server that still allows basic auth can use SYSTEMLINK_USERNAME / SYSTEMLINK_PASSWORD instead of a key. SystemLink Cloud can use the API key alone (no URI); the backend then constructs CloudHttpConfiguration.

3. Probe before MCP so a failed login cannot silently become the fake fleet:

uv run server.py --probe

You should see "simulated": false and a short query_systems preview from your server. Then launch MCP without the simulate flag, or point Cursor at .cursor/mcp.json.live.example.

If --probe fails, the JSON error is from the SDK (ApiException / connect), not from dummy data.

Tools

Tool	Access	What it answers
summarize_yield	read	Pass/fail yield, optionally grouped by part, program, or serial
query_results	read	Filtered result counts plus a bounded recent preview
get_failing_steps	read	Failing steps for one result, with measurement vs limits
summarize_measurement	read	Table stats plus a downsampled trace (decimated on the live API)
list_calibration_due	read	Assets past or approaching calibration due
query_assets	read	Inventory with presence and calibration status
query_systems	read	Registered systems and connection health
query_products	read	Products / part numbers / families
query_specs	read	Spec limits for a product
list_files	read	File metadata for a result or asset (no contents)
update_result_properties	gated write	Keywords/properties on a test result
execute_notebook	gated write	Queue a Jupyter notebook execution

MCP Inspector

From the repo root, with simulation forced:

SYSTEMLINK_MCP_SIMULATE=1 npx -y @modelcontextprotocol/inspector uv run server.py

PowerShell:

$env:SYSTEMLINK_MCP_SIMULATE="1"
npx -y @modelcontextprotocol/inspector uv run server.py

Open the printed URL (typically http://127.0.0.1:6274). Confirm the twelve tools appear, then call summarize_yield with group_by=part_number.

Streamable HTTP instead of stdio:

SYSTEMLINK_MCP_SIMULATE=1 uv run server.py --http

The MCP endpoint is http://127.0.0.1:8000/mcp. Do not use transport="sse"; that transport is deprecated.

Cursor

Use .cursor/mcp.json.example (simulator) or .cursor/mcp.json.live.example (real server). Machine-local .cursor/mcp.json is gitignored.

{
  "mcpServers": {
    "systemlink-mcp": {
      "command": "uv",
      "args": [
        "run",
        "--directory",
        "C:/Users/folayaod/personal/systemlink-mcp",
        "server.py"
      ],
      "env": {
        "SYSTEMLINK_MCP_SIMULATE": "1"
      }
    }
  }
}

Claude Desktop

Same JSON block, in claude_desktop_config.json:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json

Restart Claude Desktop after saving.

Prompts that exercise the simulated fleet

1. "What is the pass/fail yield for part number PN-5164-B, grouped against the other revisions?"
2. "DUT-1001 failed BoardFunctional.seq. Which step failed, and how did Gain compare to its limits? Summarize the attached measurement trace."
3. "Which PXI assets are overdue or approaching calibration, and is PXI Rack 1 connected?"

Tests

SYSTEMLINK_MCP_SIMULATE=1 uv run pytest

Tests hit the simulated backend only. They do not open a network connection to SystemLink.

Status

Personal project, one maintainer. The simulated backend is the supported day-to-day path. The real backend is written against nisystemlink-clients 2.32.x APIs documented at python-docs.systemlink.io and the ni/nisystemlink-clients-python source. It has not been run against a live SystemLink Enterprise instance in this repository's CI. Asset Dynamic LINQ property names for calibration status follow the PascalCase style of the official AssetIdentifier example; if a live server rejects that filter, that is a known integration risk documented in DEVLOG.md.