---
title: STDIO Mode
slug: litmus-mcp-server/stdio-mode
docTags: 
createdAt: 2026-05-11T21:40:02.822Z
---

STDIO mode runs the Litmus MCP server as a local child process of an MCP client. It is the only way to use Claude Desktop (which does not speak SSE) and is convenient for local development.

STDIO mode is **not** available from the published Docker image. You need to clone the repository and run the Python process directly.

## 1. Clone

```bash
git clone https://github.com/litmusautomation/litmus-mcp-server.git
cd litmus-mcp-server
```

## 2. Enable STDIO

Edit `src/config.py` so that:

```python
ENABLE_STDIO = os.getenv("ENABLE_STDIO", "true").lower() in ("true", "1", "yes")
```

Defaulting to `true` means the server runs in STDIO mode unless `ENABLE_STDIO=false` is passed at launch.

## 3. Install dependencies

Using `uv`:

```bash
uv sync
```

Using pip in a venv:

```bash
python -m venv .venv
. .venv/bin/activate
pip install -e .
```

## 4. Run the server

```bash
# uv
uv run python3 src/server.py

# plain Python
python3 src/server.py
```

You should see `Starting Litmus MCP Server in STDIO mode` in the log. The process now waits for an MCP client on stdin / stdout.

## 5. Wire it into an MCP client

For Claude Desktop, see [Claude Desktop](#).

For any other STDIO-capable MCP client, the pattern is:

```json
{
  "mcpServers": {
    "litmus-mcp-server": {
      "command": "/path/to/.venv/bin/python3",
      "args": [
        "/absolute/path/to/litmus-mcp-server/src/server.py"
      ],
      "env": {
        "PYTHONPATH": "/absolute/path/to/litmus-mcp-server/src",
        "EDGE_URL": "https://<LITMUSEDGE_IP>",
        "EDGE_API_CLIENT_ID": "<oauth2_client_id>",
        "EDGE_API_CLIENT_SECRET": "<oauth2_client_secret>",
        "NATS_SOURCE": "<LITMUSEDGE_IP>",
        "NATS_PORT": "4222",
        "NATS_USER": "<access_token_username>",
        "NATS_PASSWORD": "<access_token_from_litmusedge>",
        "INFLUX_HOST": "<LITMUSEDGE_IP>",
        "INFLUX_PORT": "8086",
        "INFLUX_DB_NAME": "tsdata",
        "INFLUX_USERNAME": "<datahub_username>",
        "INFLUX_PASSWORD": "<datahub_password>"
      }
    }
  }
}
```

STDIO mode reads the same credentials as SSE mode, but from process environment variables instead of HTTP headers. See [Headers Reference](#) for what each one does.

## Notes

- For dev work that bridges differing MCP library versions (e.g., `npx @modelcontextprotocol/inspector` vs `litmus-mcp-server`), point `command` at the project's venv Python so you don't pick up system-wide MCP installs. See `claude_desktop_config_venv.example.json` in the repo for a ready-to-edit template.
- Only one MCP client can attach to a given STDIO server process at a time.
- For shared or multi-user setups, use Docker SSE mode instead. See [Docker](#).