MCP Guard

Real-time security firewall for AI agents

MCP Guard

One line install, instant protection

MCP Guard is an inline security proxy between MCP clients and servers. Inspects all messages in real-time and blocks malicious tool calls before they reach the server.

46KB bundleMicrosecond inspectionZero config

Install globally:

npm install -g @aiclude/mcp-guard

claude_desktop_config.json / .cursor/mcp.json

Or add to your MCP client config:

{
  "mcpServers": {
    "my-server-guarded": {
      "command": "npx",
      "args": ["-y", "@aiclude/mcp-guard", "--", "npx", "-y", "@your/mcp-server"]
    }
  }
}

The Reality of MCP Threats

MCP has become the TCP/IP of AI agents. But existing security tools (WAF, SAST, DAST) don't understand MCP protocol.

92% Exploit Probability

With just 10 MCP plugins installed (VentureBeat)

30+ CVEs

MCP-related CVEs reported in Jan-Feb 2026 alone

OWASP MCP Top 10

Official threat classification published

3 Security Rule Engines

Full-spectrum inspection from tool definitions to tool calls to tool responses — no bypass path for attackers.

Tool Poisoning Detection

Detects hidden malicious instructions in tool descriptions: zero-width characters, homoglyphs, prompt injection, name spoofing

Argument Injection Detection

Blocks injection attacks in tool call arguments: SQL, Command, XSS, Path Traversal, Template — 21+ patterns

Data Exfiltration Detection

Detects sensitive data leaks in tool responses: credentials, system paths, stack traces

Advanced Detection Technology

Multi-layer detection engine that catches even invisible attacks.

Zero-Width Steganography

Detects 30+ invisible Unicode categories (U+200B, U+FEFF, etc.)

Homoglyph Normalization

47+ Cyrillic/Greek character mappings + NFKD normalization

Multilingual Prompt Injection

33+ injection phrases in English, Korean, Chinese, Japanese

Normalize-then-Match

Homoglyph → ASCII conversion → pattern matching to block character disguise bypass

Dual Protocol — Protection Everywhere

Local or remote, stdio or HTTP — seamless protection.

	Streamable HTTP	Legacy SSE	stdio
Supported	✅ POST/GET/DELETE	✅ GET /sse, POST /messages	✅ stdin/stdout

Why MCP Guard?

The only solution that blocks in real-time at the MCP protocol level.

Capability	MCP Guard	WAF	SAST	Manual Review
MCP Protocol Awareness	✅	❌	❌	△
Real-time Blocking	✅	✅	❌	❌
Tool Poisoning Detection	✅	❌	❌	△
Argument Injection Blocking	✅	△	✅	△
Data Exfiltration Detection	✅	△	❌	△
Multilingual Injection	✅	❌	❌	❌
Zero Config Deployment	✅	❌	❌	❌
Performance Impact	μs	ms	Offline	Offline

Install today. Tomorrow may be too late.

Pre-block, not post-report. Zero performance impact. Zero configuration.

npm install -g @aiclude/mcp-guard

npm GitHub Documentation