Kalender Sync

Answer an invitation

respond_to_event

Destructive

Accepts, declines or tentatively accepts an invitation someone else sent the user. The organiser is notified — that is the point: removing an invitation from the calendar without answering leaves them expecting the user.

The event_id comes from get_availability, for a calendar the user allowed managing (manageable: true in list_calendars).

Everything needed is in the get_availability or search_events result — pass event_id AND calendar_id straight back, and read is_recurring and is_organizer from the same entry instead of asking the user about them.

When is_recurring is true, set scope: "occurrence" answers only that date, "series" answers all of them. If the user named a date ("on Tuesday"), that IS "occurrence" — do not ask. Ask only when they named none, because declining one date and declining a standing commitment are different messages to the organiser.

Refusals name the way forward; pass them on rather than retrying.

Check status first: credits_exhausted means this call was NOT performed. Only warnings and credit information are returned in that case; no result data or write confirmation. Tell the user how to restore credits; do not retry automatically.

Input Schema

TableJSON Schema

Name	Required	Description
`scope`	No	For a recurring appointment: answer only this date ("occurrence") or every date ("series"). Required as soon as the appointment repeats.
`comment`	No	Optional note for the organiser, sent with the answer. CalDAV servers (iCloud, GMX, …) cannot carry one — the answer still goes out, and `warnings` says so.
`event_id`	Yes	The `event_id` from get_availability or search_events
`response`	Yes	The answer to send to the organiser
`calendar_id`	No	The `calendar_id` that came back beside the event. Always pass it — it is in the same result, and leaving it out costs a round trip whenever more than one calendar is available.

Output Schema

TableJSON Schema

Name	Required	Description
`needs`	No
`scope`	No
`title`	No
`status`	Yes	ok: tool executed; use its result fields. credits_exhausted: not executed; no result fields.
`event_id`	No
`question`	No
`response`	No
`warnings`	No
`resets_at`	No
`credits_required`	No
`credits_available`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedOct 18, 2026

changedInput schema / properties / comment / description

Previous value: -"Optional note for the organiser, sent with the answer"New value: +"Optional note for the organiser, sent with the answer. CalDAV servers (iCloud, GMX, …) cannot carry one — the answer still goes out, and `warnings` says so."

Changed5 schema fields changedOct 11, 2026

addedOutput schema / properties / credits_available
```
Added value: +{
+  "type": "number"
+}
```
addedOutput schema / properties / credits_required
```
Added value: +{
+  "type": "number"
+}
```

addedOutput schema / properties / resets_at

Added value: +{
+  "type": [
+    "string",
+    "null"
+  ]
+}

addedOutput schema / properties / status

Added value: +{
+  "description": "ok: tool executed; use its result fields. credits_exhausted: not executed; no result fields.",
+  "enum": [
+    "ok",
+    "credits_exhausted"
+  ],
+  "type": "string"
+}

changedOutput schema / required

Previous value: -[
-  "event_id",
-  "response"
-]New value: +[
+  "status"
+]

AddedSep 10, 2026

TDQS

A4.8/5.0

Behavior5/5

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

Goes well past the destructive/openWorld annotations: the organiser is notified, is_recurring/is_organizer can be read instead of asking, refusals name the way forward and must not be retried, and credits_exhausted means the write did NOT happen with only warnings returned. This is exactly the mutation-side disclosure annotations cannot carry.

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

Conciseness4/5

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

Front-loaded with the action and its consequence, then provenance, then scope rules, then failure handling. Dense and mostly waste-free, though the prose runs long and a bulleted shape for the scope rules would read faster.

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?

An output schema exists so return values need no explanation, and the description still covers the exception paths that matter: credits_exhausted (no write performed), warnings, and refusal messages. Nothing material for correct invocation is missing.

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 adds real decision semantics: the 'on Tuesday IS occurrence' heuristic, the rule that calendar_id should always be passed to avoid a round trip, and the provenance of event_id. It stops short of adding anything on comment beyond the schema's own CalDAV note.

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?

Opens with a precise verb+resource: accepts/declines/tentatively accepts an invitation someone else sent, and immediately contrasts with deleting an invitation from the calendar. An agent can distinguish this from create_event, update_event and delete_event without opening a 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?

Explicitly routes the agent: event_id/calendar_id come from get_availability or search_events, manageability is verified via list_calendars, and it names the alternative action (removing from the calendar) and why it is wrong. It also gives a concrete decision rule for when to ask the user about scope and when not to.

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

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