hn_explain

THE RISK

Low Risk

Why hn_explain needs a policy

This tool retrieves and returns reference information about Hacker News terminology and culture. It has no side effects, does not modify data, does not execute code or commands, and does not access external systems. It is a pure read operation with minimal risk.

From the tool's definition Tool name 'hn_explain' and description 'Get explanations of Hacker News terms, culture, and conventions' indicate a retrieval/query function that returns informational content without modifying data or triggering external operations.

Documented attack patterns abuse exactly the kind of access hn_explain gives an agent:

POLICY

How to control hn_explain

PolicyLayer is an MCP gateway — it sits between your AI agents and HN-MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for hn_explain:

policy.json

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

hn_explain is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

Create a free account and register HN-MCP — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

CAP THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More HN-MCP tools

Read browse_stories Browse Hacker News stories by type. Returns story list with scores, comments, and metadata Read get_story_details Get a Hacker News story with its comments. Fetches full story content and comment threads. Read search_hn Search Hacker News stories and comments. Returns matching content with relevance scores. Read user_analysis Analyze a Hacker News user

All 5 HN-MCP tools →

Read tools on other servers

M-Team MCP Server get_torrent_detail YouTube MCP Server search_channel Android Forensics ADB MCP Server parse_browser_history 0xarchive web3_challenge

Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about hn_explain

What does the hn_explain tool do? +

Get explanations of Hacker News terms, culture, and conventions. It is categorised as a Read tool in the HN-MCP MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on hn_explain? +

Register the HN- MCP server in PolicyLayer and add a rule for hn_explain: 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 HN-MCP. Nothing to install.

What risk level is hn_explain? +

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

Can I rate-limit hn_explain? +

Yes. Add a rate_limit block to the hn_explain 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 hn_explain completely? +

Set action: deny in the PolicyLayer policy for hn_explain. 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 hn_explain? +

hn_explain is provided by the HN- MCP server (karanb192/hn-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every HN-MCP tool call.

Start from HN-MCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →