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Vobiz MCP Server

Vobiz MCP Server

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by vobiz-ai
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TypeScript
Hybrid

Check opt-out

check_opt_out
Read-only

Check if a phone number is on this account's opt-out list for a channel and return opted_out true or false. Use before sending messages to skip blocked contacts instead of handling a refusal.

Instructions

Check whether ONE phone number is on this account's opt-out list for a channel (GET /api/v1/sms/opt-outs/{phone}) and return opted_out true or false. Call it before send_message to skip a blocked contact instead of handling the opted_out refusal. A number Vobiz has never seen is simply not opted out, so the answer is always definite. To list every blocked number use list_opt_outs; to change the list use add_opt_out or remove_opt_out.

Input Schema

NameRequiredDescriptionDefault
channelNosms (default; also covers mms), mms or rcs.
phone_numberYesThe number to check, E.164 (leading + optional).

Output Schema

NameRequiredDescriptionDefault
okNoTrue on success; false when the result is an error (then error, message and retryable are set).
channelNoChannel that was checked: sms, mms or rcs.
opted_outNoTrue when send_message would refuse this number on this channel.
phone_numberNoThe number, normalised to E.164.

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed2 schema fields changedv1.4.2
    • addedInput schema / properties / phone_number / description
      Added value: +"The number to check, E.164 (leading + optional)."
    • changedOutput schema / (root)
      Previous value: -nullNew value: +{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "additionalProperties": {},
+  "properties": {
+    "channel": {
+      "description": "Channel that was checked: sms, mms or rcs.",
+      "type": "string"
+    },
+    "ok": {
+      "description": "True on success; false when the result is an error (then error, message and retryable are set).",
+      "type": "boolean"
+    },
+    "opted_out": {
+      "description": "True when send_message would refuse this number on this channel.",
+      "type": "boolean"
+    },
+    "phone_number": {
+      "description": "The number, normalised to E.164.",
+      "type": "string"
+    }
+  },
+  "type": "object"
+}
  2. First observedv1.1.1

TDQS

A4.5/5.0
Behavior4/5

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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds genuine non-obvious behavior: the return is opted_out true/false and the answer is always definite because an unknown number is simply not opted out. It does not mention auth requirements or rate limits, but for a read-only lookup that is a minor omission.

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?

Three sentences, all load-bearing: what it does, when to call it, and where to go for the sibling operations. The primary purpose is front-loaded before the alternatives.

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 structure need not be spelled out, yet the description still states the opted_out true/false shape and the definite-answer guarantee. Combined with explicit sibling routing and a pre-send usage pattern, 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.

Parameters3/5

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

Schema description coverage is 100% – both parameters are documented in the schema, including the channel enum and the E.164 pattern. The description adds no parameter-level meaning beyond what the schema already supplies, so the baseline 3 applies.

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 (check), resource (opt-out list), scope (ONE phone number), and even the endpoint GET /api/v1/sms/opt-outs/{phone}. It explicitly differentiates from list_opt_outs, add_opt_out, and remove_opt_out, so an agent can route 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?

Gives an explicit when-to-use ('call it before send_message to skip a blocked contact instead of handling the opted_out refusal') plus named alternatives for the adjacent jobs (list_opt_outs to enumerate, add_opt_out/remove_opt_out to modify). This is a complete routing rule.

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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