GEO Shield MCP

A defensive, read-only MCP server that lets AI agents (Claude, Gemini CLI, Cursor, VS Code Copilot, Codex and others) inspect websites for manipulation aimed at search engines and AI assistants: sneaky and open redirects, hidden text and links, injected spam, hijacked metadata, hidden prompt-injection text, and "Summarise with AI" links whose prefilled prompts try to plant instructions in a visitor's assistant ("AI recommendation poisoning").

Every finding is produced by a deterministic rule and backed by evidence: location, visibility state, an excerpt, severity and confidence (kept separate), remediation, and false-positive notes. Scanned content is always treated as untrusted data.

Status: Milestone 1. geo_scan_url, geo_trace_redirects and geo_get_report are implemented and tested. See Pending for later phases.

Install

Requires Node.js ≥ 22.12 (it uses the built-in node:sqlite). No API keys are needed. Every client below runs the same command: npx -y geo-shield-mcp.

Claude Code

claude mcp add geo-shield -s user -- npx -y geo-shield-mcp

Gemini CLI

gemini mcp add geo-shield npx -y geo-shield-mcp

OpenAI Codex CLI

codex mcp add geo-shield -- npx -y geo-shield-mcp

Claude Desktop, Cursor, Windsurf, Antigravity

These clients use the same JSON shape:

{
  "mcpServers": {
    "geo-shield": {
      "command": "npx",
      "args": ["-y", "geo-shield-mcp"]
    }
  }
}

VS Code (GitHub Copilot agent mode)

.vscode/mcp.json:

{
  "servers": {
    "geo-shield": { "type": "stdio", "command": "npx", "args": ["-y", "geo-shield-mcp"] }
  }
}

ChatGPT and other web apps

Web apps such as ChatGPT can only connect to remote MCP servers over HTTPS. This release runs locally over stdio, so it works with the desktop, CLI and IDE agents above. A hosted HTTP version is planned.

From source

git clone https://github.com/krishnaGauss/MCP_WebSafe.git && cd MCP_WebSafe && npm install && npm run build

Then point your client at node /absolute/path/to/MCP_WebSafe/dist/index.js instead of npx -y geo-shield-mcp.

Related MCP server: maxaeo-ai-visibility-mcp

Usage

Ask your agent in plain language:

• "Scan https://example.com with geo_scan_url and explain anything suspicious."

• "Trace where this link really goes: https://…"

• "Check https://… for hidden AI prompt injection." (or run the investigate_ai_injection prompt)

• "Scan it again as a mobile browser and as a search crawler. Does the content change?"

• "Give me the full markdown report for scan_…"

Scans are stored locally in ~/.geo-shield/geo-shield.db and purged after 30 days by default.

Tools

Request contexts: desktop_browser, mobile_browser, search_referrer, crawler_ua_simulated. Non-browser contexts are labelled as simulations. A request from this machine is not proof of what a real crawler sees.

Resources: geo://taxonomy, geo://rules, geo://rules/{rule_id}, geo://scan/{scan_id}, geo://domain/{domain}/history Prompts: investigate_redirect, investigate_ai_injection, review_scan_findings

Rules (Milestone 1)

Full definitions (detection logic, severity mapping, remediation, false positives) are served at geo://rules.

How false positives are kept down:

• Hidden elements that match accessibility or UI patterns (sr-only, <details>, menus, tabs, modals, aria-controls targets, camelCase component classes) are counted but not flagged, unless they contain spam keywords, AI instructions or external links.

• Text hidden by a UI toggle (display:none, opacity:0, hidden) is informational unless its content is suspicious.

• Same-colour checks use the colour the text actually inherits, and are marked "unconfirmed" when no background is declared or the text sits next to an image.

• AI-instruction patterns work in families (override, persistence, exfiltration, suppression, recommendation, AI-address). Visible text needs corroborating families before it is flagged.

Security design

• SSRF: only http/https on ports 80/443 (add more with GEO_SHIELD_ALLOWED_PORTS). The scanner blocks:

  • credentials embedded in URLs

  • localhost, *.internal, *.local and single-label hostnames

  • IP literals in any encoding (decimal, hex, octal)

  • private, loopback, link-local, CGNAT and metadata ranges, for both IPv4 and IPv6 (including IPv4-mapped addresses)

• DNS rebinding: a guarded lookup inside the HTTP connector validates every resolved address at connect time, so the address it checks is the address it connects to.

• Redirects: followed manually and re-validated on every hop, with loop detection, a timeout, and a body cap (oversized bodies are truncated and flagged).

• No execution: scripts are never run, and links and "Summarise with AI" buttons are inspected statically, never followed.

• Untrusted output:

  • Excerpts are stripped of control, zero-width and bidi characters, then truncated.

  • The markdown report wraps excerpts in code spans they can't break out of.

  • Every tool result carries an untrusted-content notice.

• Privacy and logging: Set-Cookie values are never stored, and logs go to stderr only.

• Fixture mode (GEO_SHIELD_FIXTURE_ALLOW=host:port,...) is the only way to reach loopback. It's for tests only and logs a warning when set.

Configuration

See .env.example: GEO_SHIELD_DB_PATH, GEO_SHIELD_LOG_LEVEL, GEO_SHIELD_FETCH_TIMEOUT_MS, GEO_SHIELD_MAX_BODY_BYTES, GEO_SHIELD_ALLOWED_PORTS, GEO_SHIELD_RETENTION_DAYS (stored scans older than this are purged at startup), and GEO_SHIELD_FIXTURE_ALLOW.

Development

npm test

npm run lint && npm run typecheck

npm run build && npm run demo -- https://example.com

• npm run demo starts the local fixture site, launches the built server over real stdio as Claude would, and calls every tool.

• npm run fixtures runs the fixture site on its own, for use with npm run inspect (MCP Inspector).

The tests cover:

• 14+ fixture pages: clean, legitimate hidden UI, screen-reader text, white-on-white links, off-screen text, open redirect, UA- and referrer-conditional redirects, injected casino link, hidden iframe, hidden AI instructions, malicious "Summarise with AI" links, a hijacked spam page, a legitimate migration redirect, an article about prompt injection, and more

• SSRF bypass attempts

• unit tests for each rule

• an end-to-end MCP client/server test

Releasing

1. Bump the version in package.json, server.json (twice) and SERVER_INFO in src/mcp/server.ts. A test fails if they disagree.

2. Publish to npm. prepublishOnly runs type-check, lint, tests and build first:

   npm publish

3. Publish to the MCP Registry:

   mcp-publisher login github && mcp-publisher publish

Architecture

src/
  index.ts                  STDIO entry (serveStdio)
  mcp/                      tools, resources, prompts (transport layer only)
  scanner/orchestrator.ts   pipeline: validate → fetch → parse → detect → score → persist
  scanner/safe-fetch.ts     manual redirects, size/time limits, guarded DNS
  security/                 SSRF policy
  analysis/                 HTML parser, static visibility engine, keyword + AI-instruction patterns
  detectors/                redirect-abuse, hidden-content, spam-injection, ai-prompt-injection
  rules/catalog.ts          rule definitions + taxonomy
  risk/                     evidence builder, scoring
  reports/                  markdown renderer
  storage/                  SQLite (scans, pages, findings, redirect_hops)

The scanner engine is independent of MCP: ScanOrchestrator can be reused by a CLI or CI job.

Limitations

• Static analysis only: no JavaScript rendering, and external stylesheets aren't fetched. Visibility is inferred from inline styles, <style> blocks and attributes.

• Simulated contexts: request contexts are simulations, not verified crawler behaviour.

• No baseline yet: without a stored baseline, a scan can't tell when content was added.

• Indicators, not verdicts: findings call for investigation. They aren't proof of intent or of a search-policy violation.

• No ingestion proof: a page scan can't show that any AI model ingested or remembered the content.

Pending

• Phase 3 · geo_compare_page_variants (cloaking diff across contexts), Playwright rendering

• Phase 4 · geo_scan_site (sitemap + scoped crawl with authorisation), baselines, geo_diff_baseline

• Phase 4/5 · geo_audit_ugc, geo_inspect_ai_content as a focused tool, memory-poisoning consistency checks

• Phase 6 · historical comparison, finding annotations, geo://domain/{domain}/baseline