McpVanguard

Security gateway for MCP agents and tool servers.

McpVanguard sits between an AI agent and an MCP server, inspects tool traffic in real time, and enforces 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.

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.

Use Cases

• protect local desktop or developer-machine MCP servers without rewriting them

• add a hosted gateway in front of shared MCP servers

• compare raw versus guarded behavior for risky tool workflows

• add policy enforcement to high-risk file, shell, and network-access tools

Quickstart

Install the package:

pip install mcp-vanguard

Wrap a local stdio MCP server:

vanguard start --server "npx @modelcontextprotocol/server-filesystem ."

Run as a hosted gateway:

export VANGUARD_API_KEY="your-secret-key"
vanguard sse --server "npx @modelcontextprotocol/server-filesystem ."

Deploy on Railway:

Need a complete deployment walkthrough? See docs/DEPLOYMENT.md and docs/railway-deployment-guide.md.

Getting Started

Bootstrap a local workspace:

# 1. Initialize safe zones and .env template
vanguard init

# 2. Optionally update Claude Desktop server entries
vanguard configure-claude

# 3. Launch the local security dashboard
vanguard ui --port 4040

# 4. Run compliance and readiness checks
vanguard audit-compliance

How It Works

Every tool call is inspected before it reaches the upstream MCP server.

If a request is blocked, the agent receives a standard JSON-RPC error and the upstream server never sees the call.

Deployment Model

McpVanguard is best understood as a security gateway for MCP workflows.

• Local-first mode: wraps stdio MCP servers on a developer machine

• Gateway mode: exposes hardened SSE and Streamable HTTP endpoints for hosted or shared deployments

Typical path:

AI Agent -> McpVanguard -> MCP Server -> Tools / Files / External Systems

Current Capabilities

• hardened SSE and Streamable HTTP transport paths

• metadata poisoning inspection on initialize and tools/list

• JWT, JWKS, issuer, audience, claim, and scope checks for bearer-auth deployments

• server integrity and capability drift verification

• cross-server isolation and server_id traceability

• signed-manifest, provenance, detached signature, and Sigstore-backed trust verification

• benchmark and taxonomy tooling for measurable coverage

Authentication Modes

McpVanguard is local-first and supports stronger hosted-gateway controls when needed.

• stdio mode: no network auth required

• SSE / Streamable HTTP mode: supports VANGUARD_API_KEY

• Bearer / JWT mode: supports verified JWT/JWKS validation, issuer/audience/claim/scope checks, and auth-aware policy on the hosted gateway path

Semantic Backend Options

The optional Layer 2 semantic scorer supports multiple backends. The first configured backend wins.

Integrity and Trust

McpVanguard includes:

• signed upstream server manifests

• capability baselines and drift checks

• provenance verification hooks

• detached artifact-signature verification

• Sigstore bundle verification with identity and issuer constraints

This should be described as server integrity, baseline verification, and trust verification, not as a full SBOM platform.

Project Status

• 2.0.0 is the current release line

• the core gateway and integrity features are the main shipped scope

• broader research and future control-plane work are intentionally outside the core OSS release scope

See CHANGELOG.md for the release history and docs/DEPLOYMENT.md for deployment details.

Privacy

McpVanguard focuses on local inspection and gateway enforcement. See PRIVACY.md for current privacy and data-handling details.

Support

• Issues: github.com/provnai/McpVanguard/issues

• Contact: contact@provnai.com

• Security: see SECURITY.md

FAQ

Does this replace my MCP server?
No. McpVanguard sits in front of your existing MCP server and enforces policy before calls reach it.

Do I need to rewrite tools or agent code?
Usually no. Most setups start by routing one workflow through McpVanguard.

Is this only for hosted setups?
No. It supports local-first stdio wrapping and hosted gateway modes.

License

MIT License - see LICENSE.

Built by Provnai.