arc-gate-mcp

Runtime governance proxy for MCP tool calls. Blocks prompt injection and capability abuse before tool results reach your agent.

What it does

arc-gate-mcp sits between your MCP client and any MCP server. Every tool result passes through Arc Gate governance before reaching your agent — blocking prompt injection attacks that exploit the MCP trust boundary.

Installation

pip install arc-gate-mcp

Usage

arc-gate-mcp --upstream "uvx mcp-server-fetch" --policy balanced

With Claude Desktop

{
  "mcpServers": {
    "arc-gate": {
      "command": "uvx",
      "args": ["arc-gate-mcp", "--upstream", "uvx mcp-server-fetch", "--policy", "browser_agent"]
    }
  }
}

Policy modes

• balanced — general purpose

• browser_agent — web browsing agents

• finance_agent — financial data agents

• rag_assistant — document retrieval agents

• strict — maximum enforcement

Links

• Bendex Arc Platform

• PyPI

License

AGPL-3.0

Used with Heym

arc-gate-mcp is available as a template on Heym — an enterprise agent platform. Try the Governed Web Research Agent template to see Arc Gate MCP in action.