fetch_snippet_by_id

THE RISK

Low Risk

Why fetch_snippet_by_id needs a policy

This tool retrieves data (a code snippet) from the Nostr network by ID and displays it. It performs a query/fetch operation without creating, modifying, deleting, or executing anything. The action is read-only with minimal blast radius.

From the tool's definition Tool name 'fetch_snippet_by_id' and description 'Fetch and display a snippet by its ID' indicate a retrieval operation with no modification or side effects.

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

POLICY

How to control fetch_snippet_by_id

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

policy.json

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

fetch_snippet_by_id 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 MCP-NOSTR — 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 →

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EXPLORE

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All 9 MCP-NOSTR tools →

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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 fetch_snippet_by_id

What does the fetch_snippet_by_id tool do? +

Fetch and display a snippet by its ID. It is categorised as a Read tool in the MCP-NOSTR MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on fetch_snippet_by_id? +

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

What risk level is fetch_snippet_by_id? +

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

Can I rate-limit fetch_snippet_by_id? +

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

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

fetch_snippet_by_id is provided by the MCP-NOSTR MCP server (pablof7z/tenex-tools). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every MCP-NOSTR tool call.

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

CHECK YOUR STACK →