Confirm a held slot with the customer's name and phone number; this is the booking. Idempotent: confirming the same hold twice books it once and tells the business once.
| Name | Required | Description | Default |
|---|---|---|---|
| hold | Yes | The `id` of the hold to confirm. | |
| contact | Yes | The customer's own name and phone number (9 digits, or +country code and the number). Ask them; never invent one. | |
| session | Yes | The session id the hold was made in. |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the behavioral burden. It discloses idempotency (confirming twice books once) and the side effect of notifying the business once. It does not mention failure modes or required preconditions, but the core behavioral trait is well covered.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Two short sentences, no filler. The main purpose is stated first, and the idempotency note is a valuable addition. Perfectly front-loaded and economical.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given it's a simple mutation tool and the schema covers parameters, the description is adequate. It doesn't describe return values (no output schema), but for a booking confirmation the effect is clear. It could mention that a valid hold is required, but that is implied by 'Confirm a held slot'.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the schema already documents each parameter thoroughly, including the contact format and instruction to ask the customer. The description adds little beyond naming 'name and phone number', which is already in the schema. Baseline 3 applies.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the verb (confirm), the resource (a held slot), and the outcome (this is the booking). It distinguishes itself from hold_slot (which creates the hold) and cancel_booking (which cancels), and from get_booking (which reads).
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The phrase 'Confirm a held slot' implies it is used after a hold exists, and the idempotency note reassures repeated calls. It does not explicitly name alternatives or when not to use it, but the purpose is clear enough that an agent can infer the correct flow.
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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