check_spf

SERVERMcp Nettools SOURCEaaronckj/mcp-nettools

Low RISK CLASS

Category Read

Parameters 00 required

Recommended Allowedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/aaronckj-mcp-nettools/check-spf.md

WHAT IT DOES

What check_spf does on Mcp Nettools

AI agents call check_spf to retrieve information from Mcp Nettools without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

RISK

Why check_spf is rated Low

This tool retrieves and reads DNS SPF records for a domain. It performs passive network diagnostics similar to other legitimate tools on this server (DNS lookup, cert_check). There is no data modification, deletion, code execution, or financial impact. The blast radius of misuse is minimal — it only discloses publicly available DNS policy information.

From the tool's definition Tool description states it 'Looks up TXT records' and 'extracts the v=spf1 policy' — these are query/lookup operations with no side effects. The optional nameserver parameter is for selecting a resolver, not modifying data.

Risk signalsAdmin/system-level operation

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs check_spf safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Mcp Nettools, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For check_spf, this is the rule to start with:

check_spf Allowed

check_spf is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "check_spf": {}
  }
}

ALLOW ONLY THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Mcp Nettools, apply this rule, and every check_spf call is checked against it from then on.

FAQ

Questions about check_spf

What does the check_spf tool do? +

Check the SPF (Sender Policy Framework) record for a domain. Looks up TXT records at the domain root and extracts the v=spf1 policy. nameserver: optional custom resolver IP. Multiple SPF records is a misconfiguration (RFC 7208 §3.2). It is categorised as a Read tool in the Mcp Nettools MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on check_spf? +

Register the Mcp Nettools MCP server in PolicyLayer and add a rule for check_spf: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Mcp Nettools. Nothing to install.

What risk level is check_spf? +

check_spf is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit check_spf? +

Yes. Add a rate_limit block to the check_spf rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block check_spf completely? +

Set action: deny in the PolicyLayer policy for check_spf. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides check_spf? +

check_spf is provided by the Mcp Nettools MCP server (aaronckj/mcp-nettools). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

KEEP EXPLORING

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