McpVanguard

Security gateway for MCP agents and tool servers.

McpVanguard sits between an AI agent and an MCP server, normalizes and inspects tool traffic in real time, and enforces a layered policy before sensitive calls reach the underlying tool. It runs locally in front of stdio servers or as a hosted gateway over SSE and Streamable HTTP.

Product profiles — monitor, balanced, strict — let you adopt incrementally: start with audit-only discovery, move to balanced enforcement, then enable strict hardening for production-sensitive systems.

Existing MCP servers do not need to be rewritten.

Why Developers Use It

MCP workflows are powerful, but once tools touch files, shells, or networks, guardrails matter.

McpVanguard adds a runtime enforcement boundary so you can:

• keep normal tool traffic flowing
• block unsafe calls before execution
• inspect and debug policy decisions with audit logs
• adopt incrementally without rewriting existing MCP servers

What It Does

McpVanguard is for developers and platform teams who want explicit policy enforcement around MCP workflows.

• inspect MCP tool calls before execution
• block unsafe filesystem, command, and network patterns
• enforce auth, role, and scope requirements for sensitive tools
• inspect server metadata before it reaches downstream models
• track repeated suspicious behavior over time
• emit audit and telemetry signals for blocked, warned, and allowed traffic

Quick Verification Scenario

Use one raw path and one guarded path against the same MCP server.

• safe file read passes in both paths
• path traversal attempt is blocked in the guarded path
• risky network request is blocked in the guarded path
• metadata poisoning attempts are filtered or blocked before model exposure

This gives you a fast signal that policy is active and enforcement behaves as expected.

For a credential-free, synthetic check in 2.2.2, run python -m core.demo_verify. It checks a benign read and two blocked calls against the bundled in-memory