Expand a recurrence rule (RRULE) into concrete event instances.
AI agents call expand_rrule to retrieve information from Temporal Cortex Calendar MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
| Parameter | Type | Required | Description |
|---|---|---|---|
count | integer | null | — | Optional maximum number of instances to return. |
rrule | string | Yes | RFC 5545 RRULE string (e.g., "FREQ=DAILY;COUNT=5"). |
format | string | null | — | Output format: "toon" (default, token-efficient) or "json". |
dtstart | string | Yes | Local datetime string for the start (e.g., "2026-03-01T09:00:00"). |
timezone | string | Yes | IANA timezone (e.g., "America/New_York"). |
duration_minutes | integer | null | — | Duration of each event instance in minutes (default: 60). |
Parameters from the server's own tool schema.
Even though expand_rrule only reads data, uncontrolled read access leaks sensitive information and racks up API costs — an agent caught in a retry loop can make thousands of calls a minute without anyone noticing.
Attacks that exploit this kind of access
Expand a recurrence rule (RRULE) into concrete event instances. It is categorised as a Read tool in the Temporal Cortex Calendar MCP MCP Server, which means it retrieves data without modifying state.
expand_rrule accepts 6 parameters: count, rrule, format, dtstart, timezone, duration_minutes. Required: rrule, dtstart, timezone. The full parameter table on this page comes from the server's own tool schema.
Register the Temporal Cortex Calendar MCP server in PolicyLayer and add a rule for expand_rrule: 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 Temporal Cortex Calendar MCP. Nothing to install.
expand_rrule is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the expand_rrule 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.
Set action: deny in the PolicyLayer policy for expand_rrule. 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.
expand_rrule is provided by the Temporal Cortex Calendar MCP server (temporal-cortex/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.