add_cron_entry · Mcp Crontab MCP: Risk & Policy

WHAT IT DOES

What add_cron_entry does on Mcp Crontab

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

WHY IT NEEDS A POLICY

Why add_cron_entry needs a policy

Adding a cron entry creates a new scheduled task that persists in the system crontab and will execute repeatedly according to the cron schedule. This is a Write operation (creates data reversibly) rather than Destructive because cron entries can be removed via remove_cron_entry. Severity is high because an AI agent could schedule malicious, resource-intensive, or inappropriate automated tasks.

From the tool's definition Tool name 'add_cron_entry' indicates creation of cron jobs. Server description states the tool enables 'management of crontab entries' including adding new scheduled tasks.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

add_cron_entry Rate-limited

add_cron_entry 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": {
    "add_cron_entry": {
      "limits": [
        {
          "counter": "add_cron_entry_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 Crontab, so you can run agents against it safely.

FAQ

Questions about add_cron_entry

What does the add_cron_entry tool do? +

add_cron_entry. It is categorised as a Write tool in the Mcp Crontab MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on add_cron_entry? +

Register the Mcp Crontab MCP server in PolicyLayer and add a rule for add_cron_entry: 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 Crontab. Nothing to install.

What risk level is add_cron_entry? +

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

Can I rate-limit add_cron_entry? +

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

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

add_cron_entry is provided by the Mcp Crontab MCP server (jasona7/mcp-crontab-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.