cancel_reminder · Nexus Core MCP: Risk & Policy

WHAT IT DOES

What cancel_reminder does on Nexus Core

AI agents use cancel_reminder to create or update resources in Nexus Core — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Nexus Core environment.

WHY IT NEEDS A POLICY

Why cancel_reminder needs a policy

This tool modifies the state of an existing reminder by updating its status field to 'cancelled'. It is a reversible write operation (the reminder record still exists, just with a new status), so it falls under Write rather than Destructive. Misuse could cause important reminders to be silently cancelled, hence medium severity.

From the tool's definition Set reminder status to 'cancelled'

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

cancel_reminder Rate-limited

cancel_reminder 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": {
    "cancel_reminder": {
      "limits": [
        {
          "counter": "cancel_reminder_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 Nexus Core, so you can run agents against it safely.

FAQ

Questions about cancel_reminder

What does the cancel_reminder tool do? +

Set reminder status to 'cancelled'. It is categorised as a Write tool in the Nexus Core MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on cancel_reminder? +

Register the Nexus Core MCP server in PolicyLayer and add a rule for cancel_reminder: 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 Nexus Core. Nothing to install.

What risk level is cancel_reminder? +

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

Can I rate-limit cancel_reminder? +

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

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

cancel_reminder is provided by the Nexus Core MCP server (noumenon-ai/nexus-core). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.