cal_update · Outpost MCP: Risk & Policy

WHAT IT DOES

What cal_update does on Outpost

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

WHY IT NEEDS A POLICY

Why cal_update needs a policy

The tool modifies calendar data reversibly. Users can update event details, times, or other properties, and these changes can be undone or overwritten. This is a Write category operation. Severity is medium because calendar manipulation could disrupt scheduling or create confusion, but the blast radius is limited to a user's calendar without cascading effects.

From the tool's definition Tool name 'cal_update' combined with sibling tools 'cal_add', 'cal_delete', 'cal_list', 'cal_next', 'cal_today' indicates calendar management operations. The 'update' operation modifies existing calendar entries.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

cal_update Rate-limited

cal_update 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": {
    "cal_update": {
      "limits": [
        {
          "counter": "cal_update_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 Outpost, so you can run agents against it safely.

FAQ

Questions about cal_update

What does the cal_update tool do? +

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

How do I enforce a policy on cal_update? +

Register the Outpost MCP server in PolicyLayer and add a rule for cal_update: 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 Outpost. Nothing to install.

What risk level is cal_update? +

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

Can I rate-limit cal_update? +

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

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

cal_update is provided by the Outpost MCP server (signalclaude/outpost). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.