invariant-gateway/gateway/mcp

This is a work in progress implementation for MCP (Model Context Protocol) with the Gateway.

For now if the original MCP config file looks like:

{
    "mcpServers": {
        "weather": {
            "command": "uv",
            "args": [
                "--directory",
                "/ABSOLUTE/PATH/TO/PARENT/FOLDER/weather",
                "run",
                "weather.py"
            ]
        }
    }
}

Using the PyPi package

1. Modify the MCP config so that it looks like this:

  {
    "mcpServers": {
      "weather": {
        "command": "uvx",
        "args": [
          "invariant-gateway@latest",
          "mcp",
          "--project-name",
          "<your-project-name>",
          "--push-explorer",
          "--exec",
          "uv",
          "--directory",
          "/ABSOLUTE/PATH/TO/PARENT/FOLDER/weather",
          "run",
          "weather.py"
        ],
        "env": {
          "INVARIANT_API_KEY": "<Add Invariant API key here>"
        }
      }
    }
  }

Now Invariant MCP gateway will sit in between the MCP server and the MCP client and enforce the guardrails runtime. With this, you can also push the annotated traces for the MCP messages to explorer.

This moves the original command and args to the args list after the --exec flag.

All args before the --exec flag are relevant to the Invariant MCP gateway. These include:

• --project-name: With this you can specify the name of the Invariant Explorer project (dataset). The guardrails are pulled from this.
• --push-explorer: With this you can specify if you want to push the annotated traces to the Invariant Explorer. The annotated traces are pushed to the project name provided above.

Local Development

You need to:

1. Checkout the invariant-gatway repo.
2. Run python -m build. This will generate a .whl file in dist.
3. Modify the MCP config so that it looks like this:

  {
    "mcpServers": {
      "weather": {
        "command": "uvx",
        "args": [
          "--refresh",
          "--from",
          "/ABSOLUTE/PATH/TO/INVARIANT_GATEWAY_REPO/dist/invariant_gateway-<VERSION>-py3-none-any.whl",
          "invariant-gateway",
          "mcp",
          "--project-name",
          "<your-project-name>",
          "--push-explorer",
          "--exec",
          "uv",
          "--directory",
          "/ABSOLUTE/PATH/TO/PARENT/FOLDER/weather",
          "run",
          "weather.py"
        ],
        "env": {
          "INVARIANT_API_KEY": "<Add Invariant API key here>"
        }
      }
    }
  }