secretscan-mcp-server

An MCP server that scans a diff, a file's contents, or a pasted snippet for accidentally-committed secrets -- so any MCP-compatible agent can self-check its own changes before committing, opening a PR, or pasting a log excerpt anywhere. Fully local: no API key, no network call, no dependency beyond the MCP SDK and Zod.

Why

A leaked credential is one of the most common real-world causes of account and infrastructure compromise, and one of the easiest mistakes to make in a large diff -- a debug console.log with a real API key, a config file committed by accident, a .env pasted into a chat while asking for help. An agent that's about to commit, push, or share text is well positioned to catch this before it happens, if it has a cheap way to check.

Tool

scan_for_secrets

Scans text against a fixed set of provider-format signatures plus a generic, entropy-gated heuristic:

Detector	Catches
aws_access_key_id	AWS access key IDs (AKIA...)
aws_secret_access_key	AWS secret keys, when contextually labeled
github_personal_access_token / github_fine_grained_token	GitHub PATs (ghp_..., github_pat_...)
slack_token	Slack tokens (xoxb-..., etc.)
stripe_live_key / stripe_test_key	Stripe secret/publishable keys
google_api_key	Google API keys (AIza...)
npm_token	npm publish tokens (npm_...)
private_key_block	PEM private key blocks
jwt	JSON Web Tokens
generic_assigned_secret	anything assigned to a secret-sounding variable name (api_key, password, token, ...) whose value has high enough Shannon entropy to look random rather than a placeholder like "changeme"

Findings are always redacted -- AKIAIOSFODNN7EXAMPLE is reported as AKIA************MPLE (20 chars), never in full. The tool's own output is therefore safe to log or display without further propagating whatever it found.

This is a fixed-pattern + heuristic scan, not exhaustive. A clean result means "no known pattern matched," not "definitely safe" -- the in-app output says so explicitly.

Install and configure

git clone https://github.com/wedo911/secretscan-mcp-server.git
cd secretscan-mcp-server
npm install
npm run build

Add it to your MCP client's config (e.g. claude_desktop_config.json, or a project's .mcp.json for Claude Code):

{
  "mcpServers": {
    "secretscan": {
      "command": "node",
      "args": ["/absolute/path/to/secretscan-mcp-server/dist/index.js"]
    }
  }
}

Run the tests

npm run build
node --test tests/entropy.test.mjs tests/detectors.test.mjs

24 tests, including one for every named detector, the placeholder- and low-entropy-filtering behavior of the generic detector, and an explicit check that redacted output never contains the full secret value.

Try it without a client

npx @modelcontextprotocol/inspector --cli node dist/index.js \
  --method tools/call --tool-name scan_for_secrets \
  --tool-arg text='aws_access_key_id = AKIAIOSFODNN7EXAMPLE'

(That's AWS's own publicly documented example key -- not a real credential.)

License

MIT — see LICENSE.