@guardbee/mcp-audit-gap-auditor

@guardbee/mcp-audit-gap-auditor

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An MCP server that audits MCP server source for OWASP MCP08:2025 — Lack of Audit and Telemetry.

security-proxy already writes a hash-chained audit log at the gateway. This package asks a different question: does the MCP server itself leave a usable, non-leaky trail when a tool runs?

Telemetry is off by default. With GUARDBEE_TELEMETRY=1 it sends the server, tool, success, duration and short parameter values such as a file path; longer strings and fields like content, token or password are replaced with a placeholder. See @guardbee/mcp-telemetry.

Claude ──► audit-gap-auditor ──► MCP server source
              │
              ├─ missing-telemetry  (tools registered, no audit/log/telemetry of invocations)
              ├─ unsafe-logging     (raw tool args or results written to logs)
              ├─ disabled-audit     (audit/telemetry hard-disabled in source)
              └─ silent-failure     (tool errors swallowed with an empty catch)

What it flags

Pattern	Severity	OWASP	Meaning
mcp_server_without_tool_audit	high	MCP08:2025	McpServer / FastMCP registers tools but the file never mentions audit/telemetry
raw_tool_args_logged	critical	MCP08:2025	console/logger logs the full args/params/input object
raw_tool_result_logged	high	MCP08:2025	Full result / toolResult logged
audit_disabled_in_code	high	MCP08:2025	audit: false, enableAudit: false, GUARDBEE_TELEMETRY=0, …
tool_error_swallowed_silently	medium	MCP08:2025	Empty / return-only catch around a tool handler
audit_log_without_correlation_id	medium	MCP08:2025	audit.log({…}) with no sessionId / requestId / similar

Logging checks only run in files that look like MCP tool servers, so ordinary console.log(args) helpers elsewhere are ignored.

Quick start

{
  "mcpServers": {
    "guardbee-audit-gap-auditor": {
      "command": "npx",
      "args": ["-y", "@guardbee/mcp-audit-gap-auditor"]
    }
  }
}

npx @guardbee/mcp-audit-gap-auditor scan ./src --fail-on=high --format=sarif > results.sarif

Tools

Tool	Purpose
scan_text	Scan a source string
scan_file	Scan one file
scan_directory	Recursive scan
list_patterns	List MCP08 checks

guardbee.yml:

audit-gap-auditor:
  fail-on: high
  max-files: 5000
  exclude:
    - "fixtures/"

Feedback

Questions, ideas, or a false positive? Start a thread in GitHub Discussions or open an issue. If GuardBee is useful to you, a ⭐ on the repository helps others find it.