replyToEvent · Nostr Tools for AI Agents MCP: Risk & Policy

WHAT IT DOES

What replyToEvent does on Nostr Tools for AI Agents

AI agents use replyToEvent to create or update resources in Nostr Tools for AI Agents — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Nostr Tools for AI Agents environment.

WHY IT NEEDS A POLICY

Why replyToEvent needs a policy

This tool creates new content on a decentralized social network. While not destructive and not financial, it modifies the state of the network by adding a new event. The severity is medium because: (1) replies are user-generated content that can be deleted, (2) the blast radius of misuse is limited to unwanted replies/spam rather than financial loss or permanent data destruction, and (3) Nostr is a public protocol…

From the tool's definition 'Reply to an event' creates new data (a reply message) on the Nostr network. The description indicates this tool composes and publishes a response, which is a reversible write operation following NIP-10 threading standards.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

replyToEvent Rate-limited

replyToEvent stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "replyToEvent": {
      "limits": [
        {
          "counter": "replytoevent_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Nostr Tools for AI Agents, so you can run agents against it safely.

FAQ

Questions about replyToEvent

What does the replyToEvent tool do? +

Reply to an event with NIP-10 threading. It is categorised as a Write tool in the Nostr Tools for AI Agents MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on replyToEvent? +

Register the Nostr Tools for AI Agents MCP server in PolicyLayer and add a rule for replyToEvent: 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 Nostr Tools for AI Agents. Nothing to install.

What risk level is replyToEvent? +

replyToEvent is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit replyToEvent? +

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

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

replyToEvent is provided by the Nostr Tools for AI Agents MCP server (jorgenclaw/nostr-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.