whatsmcp

Start an AI Voice-Agent Call

wa_ai_call_start

Have an AI voice agent call a WhatsApp number from one of your numbers, using a preset from wa_ai_list_presets. Pass per-call context in variables. Returns immediately with a call_ref; the call then rings and runs on its own. Poll wa_ai_call_get about every 30 seconds until status is done, failed, no_answer or busy — then it carries the summary, transcript, collected data and a recording link. One call at a time per number; a number that just finished a call must wait a moment.

Input Schema

TableJSON Schema

Name	Required	Description
`to`	Yes	the WhatsApp number to call, international format, e.g. +447700900123
`preset`	Yes	the preset name, from wa_ai_list_presets
`variables`	No	per-call context for the agent: flat string/number/boolean values, merged over the preset's defaults, e.g. {"customer_name":"Ann","order_id":"A-1042"}
`first_message`	No	override what the agent says first on this call

Output Schema

TableJSON Schema

Name	Required	Description
`next`	No	what to do next
`status`	No	dialing once accepted
`refusal`	No	present only when the call was not placed
`call_ref`	No	pass to wa_ai_call_get to follow the call

Schema Changelog

Changes observed during successful MCP inspections.

Changed3 schema fields changedOct 14, 2026

addedOutput schema / properties / refusal / properties / account_status

Added value: +{
+  "description": "when the number is not working: its status — starting, not_running, whatsapp_down, suspended, pairing, unlinked or locked",
+  "type": "string"
+}

addedOutput schema / properties / refusal / properties / account_status_reason

Added value: +{
+  "description": "the detail of account_status, e.g. no_egress, stopped, no_plan",
+  "type": "string"
+}

addedOutput schema / properties / refusal / properties / since

Added value: +{
+  "description": "when the number stopped working, RFC3339, when known",
+  "type": "string"
+}

First observedSep 27, 2026

TDQS

A4.7/5.0

Behavior5/5

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

Annotations only cover the safety profile (not read-only, not idempotent, not destructive). The description goes well beyond by disclosing the asynchronous contract ('returns immediately with a call_ref; the call then rings and runs on its own'), the polling cadence and terminal statuses, the payload available at completion, and the per-number concurrency/cooldown limit.

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?

Four sentences, no filler, and the ordering follows the agent's decision path: what it does, what to pass, what happens next, how to follow up, then the constraint. Every sentence carries distinct information.

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?

For an async, multi-step tool this covers the full lifecycle: trigger, immediate return, poll target with interval and stop conditions, resulting artifacts, and the rate/concurrency limitation. With an output schema present it correctly needn't restate return field shapes.

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%, so each of the four parameters is already documented in the schema with format and examples. The description only adds 'Pass per-call context in variables' and repeats the preset source, which the schema descriptions already say, so the baseline of 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?

The opening sentence states a specific verb and resource ('Have an AI voice agent call a WhatsApp number from one of your numbers') and pins the required input to its source ('using a preset from wa_ai_list_presets'). This cleanly separates it from siblings like wa_ai_call_get, wa_ai_call_hangup and wa_send_message without needing 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?

It gives an explicit operational flow: call this, then poll wa_ai_call_get about every 30 seconds until one of four named terminal statuses. It also names where presets come from and states the concurrency constraint ('one call at a time per number; a number that just finished a call must wait a moment'), which tells the agent when a call will be rejected.

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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