Gateway MCP server

Vengtoo MCP Gateway

Authorization gateway for AI agents and MCP tool calls.

Open-source. Drop-in. Works with any MCP client.

Why

AI agents connected to MCP servers can call any tool they have access to: read your database, delete files, execute arbitrary SQL. Vengtoo MCP Gateway puts a policy enforcement point between the agent and those tools, so every call is authorized before it executes.

What it does

• Sits between MCP clients (Claude Code, Cursor, VS Code, GitHub Copilot) and any MCP server
• Intercepts every tool call and checks authorization before forwarding
• Two modes: cloud (Vengtoo Cloud API) and local (Vengtoo Agent + .rego policy file)
• Full audit trail of every tool invocation: subject, tool name, arguments, and decision are logged as structured JSON:

{"ts":"2026-05-25T10:03:11.482Z","level":"info","msg":"mcp_tool_call","subject":"agent:ai-assistant","tool":"database__query","allowed":true,"latency_ms":0.8}

Quick Start

1. Install and start the Vengtoo Agent. The agent runs locally and evaluates your authorization policy; no cloud account needed.

go install github.com/vengtoo/agent/cmd/agent@latest
vengtoo-agent --policy ./policy.rego

Create a policy.rego to define what your agent can do:

package vengtoo.mcp

default allow := false

# Allow read-only tools
allow if { input.resource.name == "database__query" }
allow if { input.resource.name == "database__list_tables" }

# Allow writes, but block destructive SQL
allow if {
    input.resource.name == "database__execute"
    not contains(lower(input.resource.attributes.sql), "drop")
    not contains(lower(input.resource.attributes.sql), "delete from")
}

See demo/policies/ for more examples including Kubernetes namespace protection.

1. Create a gateway.config.json:

{
  "vengtoo": {
    "agentUrl": "http://127.0.0.1:8181"
  },
  "subject": "agent:ai-assistant",
  "servers": {
    "database": {
      "command": "node",
      "args": ["./my-database-mcp-server.js"]
    }
  }
}

1. Add to your MCP client (e.g. Claude Code):

claude mcp add --transport stdio vengtoo-gateway -- \
  npx vengtoo-mcp-gateway --config /path/to/gateway.config.json

Configuration

Config schema

Shortened. The full README is on GitHub.