@guardbee/mcp-elicitation-auditor

@guardbee/mcp-elicitation-auditor

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An MCP server that scans MCP server source for elicitation anti-patterns in the 2026-07-28 specification.

That revision deprecated sampling and roots. Elicitation is the remaining way a server asks the client for something. Form mode collects structured data through the client. URL mode sends the user to a page the client must not read. The spec draws a hard line between them.

This package sends usage telemetry by default (tool name + short parameters, scanned code is never included — see @guardbee/mcp-telemetry). Disable with GUARDBEE_TELEMETRY=0.

Claude ──► elicitation-auditor ──► MCP server source
              │
              ├─ form-secrets   (form mode asks for a password, API key, token, or card, or embeds a link)
              ├─ url-binding    (URL mode opens a third-party /authorize endpoint directly)
              ├─ url-exposure   (credential or email embedded in the elicitation URL)
              ├─ transport      (cleartext http URL outside localhost)
              ├─ identity       (a form answer is treated as who the user is)
              └─ completion     (the result is used without checking decline or cancel)

What it flags

• Form-mode secrets. elicitInput / ctx.elicit / elicitation/create with mode omitted or form, whose schema asks for password, apiKey, access_token, cvv, and the same family. A name and email form is allowed by the spec and is not flagged. secretQuestion is not treated as secret.
• Direct third-party authorize. URL mode whose url path contains authorize, oauth, or oauth2, unless the path goes through your own /connect route. That is the forwarded-link phishing case in the spec: the user who opens the link must be checked against the MCP user before any redirect.
• Credential or personal data in the URL. Query keys such as access_token, code, or email. The URL is shown to the MCP client.
• Cleartext HTTP, except localhost and 127.0.0.1.
• Clickable URL in a form. A form message or field description that contains an http link. The spec says that link belongs in URL mode.
• Form answer used as identity. The submitted email or username is passed to findUser, loginAs, or assigned to req.user, with no comparison to the token sub claim.
• Ignored decline/cancel. Code reads .content and never looks at .action, decline, or cancel. Checking action !== "accept" is enough. Sending the email as a notification address is not treated as an identity check.

Tools

Tool	Purpose
scan_text	Scan a source string
scan_file	Scan one file
scan_directory	Recursive scan
list_patterns	List the checks

CLI

npx @guardbee/mcp-elicitation-auditor scan <path> [--fail-on=any] [--format=text|json|sarif]

guardbee.yml:

elicitation-auditor:
  fail-on: high
  max-files: 5000
  exclude:
    - ".test.ts"

No API key. Static analysis only.