LobbyStack

Book an appointment

book_appointment

Books an appointment at an open time from check_availability. Works only when booking_mode is instant; otherwise it fails with booking_requires_confirmation or booking_disabled, and you should tell the owner instead of retrying. Identify the customer with contact_id (a contact that has a phone number) or contact_phone. Fails with slot_unavailable if the time was taken; check availability again and offer another time. Confirm the service, time and customer with the owner before calling.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "service_id": "<service_id>",
      "starts_at": "<starts_at>"
    },
    "name": "book_appointment"
  }
}

Input Schema

Name	Required	Description
`staff_id`	No	Preferred staff member, if the customer asked for one.
`starts_at`	Yes	A starts_at value from check_availability, unchanged.
`contact_id`	No	An existing contact that has a phone number. Give contact_id or contact_phone.
`service_id`	Yes	The service id (UUID).
`sms_consent`	No	True only if the customer agreed to confirmation and reminder texts. Never assume it. Has no effect on LobbyStack Cloud, where only the receptionist collects text consent, on a call.
`contact_name`	No	Customer name, used when a new contact is created.
`contact_phone`	No	Customer phone in E.164 format. A new contact is created if none has this number.
`idempotency_key`	No	Optional. A unique value you choose, such as a UUID. Retrying with the same value within 24 hours returns the first result instead of creating a duplicate.

Output Schema

Name	Required	Description
`id`	Yes	Stable identifier (UUID).
`notes`	Yes	Notes on the appointment. The receptionist can read them to a verified caller.
`source`	Yes	Where the booking came from, for example voice, web_chat, dashboard or api.
`status`	Yes
`ends_at`	Yes	ISO 8601 timestamp in UTC.
`staff_id`	Yes	Stable identifier (UUID).
`timezone`	Yes
`starts_at`	Yes	ISO 8601 timestamp in UTC.
`contact_id`	Yes	Stable identifier (UUID).
`created_at`	Yes	ISO 8601 timestamp in UTC.
`service_id`	Yes	Stable identifier (UUID).
`staff_name`	Yes
`updated_at`	Yes	ISO 8601 timestamp in UTC.
`contact_name`	Yes
`service_name`	Yes
`contact_phone`	Yes
`calendar_sync_status`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedNov 12, 2026

TDQS

A4.1/5.0

Behavior3/5

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

Annotations already declare this is a non-read-only, non-destructive, non-idempotent write, and the description adds valuable failure modes (booking_requires_confirmation, booking_disabled, slot_unavailable) and an explicit no-retry policy. It does not discuss permission or auth requirements, though the output schema covers return values. Strong on error behavior, silent on authorization.

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 main precondition, then layered with failure handling and the confirmation rule; every sentence carries operational weight. Slight redundancy with the schema around contact_id and contact_phone keeps it from a 5.

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

Completeness4/5

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

Covers the prerequisites, main failure branches, customer identification, and the human-confirmation step for an 8-parameter mutation tool with an output schema. What remains unsaid (auth scopes, side effects such as notifications sent) is minor given the annotation coverage and output schema.

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

Parameters3/5

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

Schema coverage is 100%, so the schema already documents service_id, starts_at, contact_id/contact_phone and idempotency_key in detail. The description reinforces the either/or customer identification rule and the 'unchanged from check_availability' constraint, but adds little that the schema does not already state. Baseline 3 is appropriate.

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?

States a specific verb and resource ("Books an appointment") plus the precondition that the time must come from check_availability, which cleanly separates it from that sibling. An agent knows exactly what this tool does without opening the 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 gates use on booking_mode being instant and names the alternatives when it is not (tell the owner instead of retrying). It also prescribes recovery for slot_unavailable (re-check availability, offer another time) and requires confirming service, time and customer with the owner before calling.

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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