@ciphyrshq/mcp-proxy

Transparent MCP proxy that intercepts tool results and masks PII before they reach any LLM. Wrap any existing MCP server (filesystem, postgres, GitHub, Slack, etc.) with zero code changes.

Quick Start

Claude Desktop

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "postgres-safe": {
      "command": "npx",
      "args": [
        "-y", "@ciphyrshq/mcp-proxy",
        "--target", "npx -y @modelcontextprotocol/server-postgres postgresql://localhost/mydb",
        "--api-key", "cyp_live_xxxxxxxxxxxx"
      ]
    }
  }
}

Cursor

Add to .cursor/mcp.json:

{
  "mcpServers": {
    "postgres-safe": {
      "command": "npx",
      "args": [
        "-y", "@ciphyrshq/mcp-proxy",
        "--target", "npx -y @modelcontextprotocol/server-postgres postgresql://localhost/mydb",
        "--api-key", "cyp_live_xxxxxxxxxxxx"
      ]
    }
  }
}

Claude Code

claude mcp add postgres-safe -- npx -y @ciphyrshq/mcp-proxy \
  --target "npx -y @modelcontextprotocol/server-postgres postgresql://localhost/mydb" \
  --api-key "cyp_live_xxxxxxxxxxxx"

Options

| Flag | Required | Default | Description | |------|----------|---------|-------------| | --target | Yes | — | The MCP server command to wrap | | --api-key | Yes* | — | Your Ciphyrs API key (cyp_live_...) | | --api-url | No | https://www.ciphyrs.com | Override for VPC/on-prem deployments | | --entities | No | all | Comma-separated PII types: PERSON,EMAIL_ADDRESS,PHONE_NUMBER | | --action | No | mask | mask = replace PII with tokens, audit = log only | | --no-mask | No | false | Transparent proxy (no masking at all) | | --session-id | No | auto-generated | Custom session ID for vault lookup |

*Required unless --no-mask is set

How It Works

LLM Host (Claude/Cursor)
    ↓ tools/call
@ciphyrshq/mcp-proxy
    ↓ forward request
Target MCP Server (postgres/filesystem/etc.)
    ↓ return results
@ciphyrshq/mcp-proxy → detects & masks PII via Ciphyrs API
    ↓ masked results
LLM Host (sees XXXX instead of real PII)

1. tools/list — forwarded as-is (no PII in tool definitions)
2. tools/call — forwarded to target, then result text is scanned for PII and masked
3. resources/read — forwarded to target, then resource text is masked
4. prompts/ — forwarded as-is (no user data in prompts)

Get Your API Key

1. Sign up at ciphyrs.com
2. Go to Dashboard → API Keys
3. Create a key with scan scope

License

MIT