CLI

Start Proxy

Start the guardrails proxy in front of an MCP server:

open-mcp-guardrails [options] -- <command> [args...]

Arguments

Argument	Description
-c, --config <path>	Config file path (optional — auto-discovered if omitted)
--	Separator between guardrails args and server command
<command> [args...]	Backend MCP server command

Config Resolution

When -c is not specified, open-mcp-guardrails searches in this order:

1. ./guardrails.config.ts (current directory)
2. ./guardrails.json (current directory)
3. $XDG_CONFIG_HOME/open-mcp-guardrails/guardrails.config.ts (defaults to ~/.config/open-mcp-guardrails/guardrails.config.ts)
4. $XDG_CONFIG_HOME/open-mcp-guardrails/guardrails.json (defaults to ~/.config/open-mcp-guardrails/guardrails.json)

TypeScript configs take priority over JSON when both exist in the same directory.

Examples

# Auto-discover config from current directory
open-mcp-guardrails -- \
  bunx @modelcontextprotocol/server-filesystem /tmp

# Explicit config path
open-mcp-guardrails -c guardrails.config.ts -- \
  bunx @modelcontextprotocol/server-github

init

Generate a config file template. Running without flags shows an interactive prompt:

$ open-mcp-guardrails init

  Select config format:
    1) TypeScript  (guardrails.config.ts)
    2) JSON        (guardrails.json)

  Choice [1]:

Use --json to skip the prompt and generate JSON directly:

open-mcp-guardrails init --json

Creates guardrails.config.ts or guardrails.json in the current directory.

check

Validate a config file (supports both .ts and .json):

open-mcp-guardrails check [-c <config>]

Example

open-mcp-guardrails check
# Config is valid. (guardrails.config.ts)
#   Rules: pii-error, secrets-error

open-mcp-guardrails check -c guardrails.json
# Config is valid. (guardrails.json)
#   Rules: pii-error, secrets-warn

schema

Print the JSON Schema to stdout:

# Print to stdout
open-mcp-guardrails schema

# Save to file
open-mcp-guardrails schema > guardrails.schema.json

Useful for editor configuration, CI pipelines, and external tooling.

Other Options

Option	Description
-h, --help	Show help
-v, --version	Show version