cron_add · MCP Cron Server MCP: Risk & Policy

WHAT IT DOES

What cron_add does on MCP Cron Server

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

WHY IT NEEDS A POLICY

Why cron_add needs a policy

This tool creates a new scheduled task in the system. Creating a scheduled task is a Write operation (reversible via cron_remove). However, severity is high because a misused scheduled task could trigger repeated arbitrary executions, cause resource exhaustion, or schedule destructive operations — amplifying any downstream harm through automation.

From the tool's definition 添加定时任务 (Add scheduled task) — creates a new cron job/scheduled task

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

cron_add Rate-limited

cron_add 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": {
    "cron_add": {
      "limits": [
        {
          "counter": "cron_add_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 MCP Cron Server, so you can run agents against it safely.

FAQ

Questions about cron_add

What does the cron_add tool do? +

添加定时任务。支持三种调度类型：at（一次性）、every（间隔）、cron（表达式）。Cron 表达式会在创建前进行语法验证。. It is categorised as a Write tool in the MCP Cron Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on cron_add? +

Register the MCP Cron Server MCP server in PolicyLayer and add a rule for cron_add: 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 Cron Server. Nothing to install.

What risk level is cron_add? +

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

Can I rate-limit cron_add? +

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

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

cron_add is provided by the MCP Cron Server MCP server (nolan57/opencode-mcp-cron). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.