create_event · Nexus Core MCP: Risk & Policy

WHAT IT DOES

What create_event does on Nexus Core

AI agents use create_event 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 create_event needs a policy

This tool creates or modifies calendar data reversibly. The event can be edited or deleted later, making it a Write rather than Destructive action. The severity is medium because misuse could create spam events, pollute the calendar with false entries, or interfere with scheduling, but the impact is limited to the calendar domain and reversible.

From the tool's definition Tool creates a calendar event with start/end times and optional recurring rules (RRULE). The description explicitly states 'Create a calendar event', which is a write operation that adds new data to a calendar system.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

create_event Rate-limited

create_event 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": {
    "create_event": {
      "limits": [
        {
          "counter": "create_event_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 create_event

What does the create_event tool do? +

Create a calendar event. start/end ISO-8601. recurring = RRULE string (e.g. 'FREQ=WEEKLY;COUNT=10'). 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 create_event? +

Register the Nexus Core MCP server in PolicyLayer and add a rule for create_event: 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 create_event? +

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

Can I rate-limit create_event? +

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

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

create_event 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.