hail

Official

by hail-hq

Overview Schema Source Related Servers Discussions Admin

Python

Hybrid

Cancel a verification

cancel_verification

Destructive

Cancels an unsent or rejected verification, discards its draft, and allows resubmission for the same country and number type; also dismisses approved US SMS registrations.

Instructions

Cancel a verification that has not been sent for review, or dismiss a rejected one (needed before submitting a new one for the same country and number type). The draft is discarded.

    Works in state ``awaiting_review`` or ``rejected``, and for an
    ``approved`` US SMS registration (``purpose: "sms"``): its numbers
    leave the campaign, US-to-US texts from them fail again, and its
    monthly fee stops after the current month. Some registrations bill at
    least 3 monthly fees from approval, so cancelling sooner can still
    charge 3 months. Ask the user first. A
    ``submitting`` or ``submitted`` verification is under review and
    cannot be cancelled (409): wait for the result with get_verification.

    Returns the verification with ``state: "cancelled"``, or
    ``{"error": "<message>"}``.

Input Schema

Name	Required	Description	Default
`verification_id`	Yes

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.29.0Oct 21, 2026

TDQS

A4.4/5.0

Behavior5/5

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

Beyond the destructive and open-world annotations, the description discloses concrete consequences: the draft is discarded, numbers leave the campaign, US-to-US texts fail again, monthly fees stop after the current month, and at least three monthly fees may still be charged. It also surfaces the user-consent requirement and the 409 behavior for in-flight verifications.

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?

The definition is front-loaded with the core action and invocation states, then adds only decision-relevant consequences such as billing risk and the user-confirmation requirement. Despite its detail, every section helps an agent decide whether and how to call the tool.

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?

The description is rich for a destructive state-changing tool: it states lifecycle applicability, side effects, billing caveats, error behavior, and return shape. The only material omission is how the agent should obtain the required verification_id, which is left implicit despite no schema description.

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

Parameters2/5

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

The sole parameter, verification_id, has 0% schema description coverage, and the description does not explain where the ID comes from, its format, or which sibling tool supplies it. The parameter name is self-evident, but the description does not compensate for the missing schema semantics.

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?

The description states a specific verb and resource ('Cancel a verification' / 'dismiss a rejected one') and scopes it to verification states and one approved US SMS registration case. It clearly distinguishes cancellation from verification workflows handled by get_verification and submit_verification.

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?

It gives explicit when-to-use conditions: awaiting_review, rejected, or approved US SMS registrations, plus the need to dismiss a rejected verification before submitting a new one for the same country and number type. It also states when not to use it (submitting/submitted, 409) and directs the agent to get_verification instead.

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