Tanod MCP server

utilpeek: list the occurrences of a recurrence rule (RRULE) in a time zone

expand_rrule

Read-onlyIdempotent

Convert an iCalendar RRULE into its occurrence list, preserving wall-clock times across DST in an IANA time zone; filter by [from, to], until, or exdates.

Instructions

utilpeek: Expand an iCalendar RRULE into dates. For cron use cron_next_runs; to build an event use build_ics_event. Returns an RFC 5545 RRULE and a start expanded into its occurrence list with python-dateutil in an IANA time zone: wall-clock times keep across DST changes. Up to 1,000 occurrences, an optional [from, to] window, extra until and exdates. Returns ISO 8601 times with offset and whether more exist. Pure computation: no network access, nothing stored. The search stops at search_horizon (1 hour for SECONDLY up to 100 years for YEARLY) and after 1.5 s. A bad rule, a rule that never matches (Feb 31) or a bad date or zone is a 422 (not charged). Typically under 0.1 s. Price: USD 0.001. Free: 10 utilpeek calls per IP per UTC day. Docs: https://tanod.dev/learn/ics-calendar-api.html

Input Schema

TableJSON Schema

Name	Required	Description
`limit`	No	Most occurrences to return (1-1000).
`rrule`	Yes	RFC 5545 RRULE, with or without the RRULE: prefix.
`until`	No	Extra upper bound (ISO 8601).
`between`	No	[from, to] ISO 8601 window (inclusive).
`dtstart`	Yes	ISO 8601 first occurrence (date or datetime).
`exdates`	No	ISO 8601 occurrences to leave out.
`timezone`	No	IANA zone the rule runs in (wall-clock times keep across DST). Default UTC.

Output Schema

TableJSON Schema

Name	Required	Description
`note`	No
`count`	No
`error`	No	Only on an error result: an object {code, message}, or the reason string of an x402 PaymentRequired object.
`rrule`	No
`dtstart`	No
`timezone`	No
`truncated`	No
`occurrences`	No
`search_horizon`	No
`horizon_reached`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.3.0Oct 15, 2026

TDQS

A4.9/5.0

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Beyond the annotations (readOnly/idempotent/non-destructive), the description discloses hard limits (1,000 occurrences, search_horizon from 1 hour to 100 years), a 1.5 s stop, 422 error semantics for bad rules/zones (not charged), typical latency, DST wall-clock preservation, cost and free-tier throttling. This is unusually rich behavioral context the annotations do not carry.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Single dense paragraph, front-loaded with purpose then sibling routing, then behavior/cost. Every sentence carries operational value (limits, errors, price, docs); none is filler despite the length, which is justified by the tool's complexity.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With an output schema present, the description need not explain return structure, and it still summarizes it (ISO 8601 with offset, 'whether more exist'). For a 7-param paid computation tool it covers limits, failure modes, DST, cost and latency — an agent has everything needed to call it correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3, but the description still adds meaning: the [from, to] window is inclusive, until is an 'extra' bound layered on the rule, exdates are omitted occurrences, and timezone governs wall-clock retention across DST. It does not, however, add syntax/format detail beyond the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

Starts with a precise verb+resource ('Expand an iCalendar RRULE into dates') and immediately names the two nearest siblings it is not: cron_next_runs (cron) and build_ics_event (build an event). An agent can route correctly without opening any schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicit when-to-use-this vs. the alternative tools ('For cron use cron_next_runs; to build an event use build_ics_event'), plus context on when it is appropriate (expanding a rule into an occurrence list). Nothing is left to inference.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Deploy Server