Rule catalog · Tool surface risk

No outbound-messaging tools in the public surface

no_public_send_message_toolshighweight 6Post-handshake

Authored by Stanley Hong · AgentReserve (founder).

No advertised tool sends an outbound message on the operator's behalf (send_email, send_sms, post_message, broadcast, notify, …). Messaging tools enable spam, phishing and impersonation if exposed without scoped review.

When this rule runs

Requires a successful MCP `initialize` / `tools/list`. Skipped on perimeter-only scans where the server refused or failed the MCP handshake.

Why it matters

Outbound-messaging tools speak with the operator's identity. Exposed without scoped review, they enable spam, phishing and impersonation against third parties.

Pass condition

No tool advertises outbound messaging (send_email, send_sms, post_message, broadcast, notify, …).

Fail condition

At least one tool surfaces outbound-messaging vocabulary.

Evidence examples

When the rule fails, the report records evidence in roughly this shape:

  • {"matches": [{"toolName": "send_email", "keyword": "send_email", "source": "name"}]}

Remediation

Restrict messaging tools to authenticated callers, scope them to specific recipients or templates, and add per-call approval for anything that reaches outside the operator's domain.

Methodology

This rule belongs to the Tool surface risk dimension. What an agent could do if it trusted every advertised tool. Covers destructive actions, credential disclosure, code execution, filesystem mutation, PII handling, prompt-injection-shaped input fields, and injection-bearing tool descriptions — i.e. the agent-specific threat surface, not just generic verb risk.

Read the full methodology for how rules are aggregated into a score, how verdicts are decided, and how hard-fail rules override the aggregate.