WhatsMCP: MCP for WhatsApp

Update Participants

wa_update_participants

Add members to a WhatsApp group (action=add), make members admins (action=promote), or make admins ordinary members again (action=demote), by phone number or JID. Adding needs the account to be a member (and, for private groups, an admin); promote and demote need an admin. To remove members, use wa_remove_participants.

Input Schema

Name	Required	Description
`action`	Yes	add (new members), promote (members to admin) or demote (admins to members); to remove members use wa_remove_participants
`members`	Yes	members — phone numbers (E.164) or JIDs, comma- or space-separated
`group_jid`	Yes	the group (…@g.us) JID, as returned by wa_list_groups
`account_id`	Yes	the account, as returned by wa_list_accounts

Output Schema

Name	Required	Description
`items`	No	the rows of a list operation
`status`	Yes	ok (the operation succeeded) or refused (see refusal; for wa_update_group, applied lists the changes that took effect before it)
`applied`	No	wa_update_group only: the settings that were changed, in order — on a refusal, the ones that took effect before it
`refusal`	No	present only when status is refused
`summary`	No	a human-readable result
`group_jid`	No	the new group's JID (wa_create_group only) — use it as wa_send_message's 'to'
`invite_link`	No	the group's invite link (wa_create_group or wa_get_group_invite_link)

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedOct 26, 2026

addedOutput schema / properties / refusal / properties / candidates

Added value: +{
+  "description": "on an account_ambiguous refusal: the accounts to choose from — retry with one of these as account_id",
+  "items": {
+    "additionalProperties": false,
+    "properties": {
+      "account_id": {
+        "description": "the id to retry with as account_id",
+        "type": "string"
+      },
+      "name": {
+        "description": "the account's WhatsApp display name",
+        "type": "string"
+      },
+      "phone": {
+        "description": "the account's phone number, E.164",
+        "type": "string"
+      },
+      "status": {
+        "description": "whether the number works right now — live, connecting, or why not, as wa_list_accounts reports it",
+        "type": "string"
+      }
+    },
+    "required": [
+      "account_id"
+    ],
+    "type": "object"
+  },
+  "type": [
+    "null",
+    "array"
+  ]
+}

Changed3 schema fields changedOct 11, 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"
+}

AddedSep 22, 2026

TDQS

A4.4/5.0

Behavior4/5

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

Annotations already declare non-read-only, non-idempotent, non-destructive; the description adds genuinely useful behavioral context on authorization requirements per action and per group type. It does not disclose what happens on duplicate adds or re-promoting an existing admin (relevant since idempotentHint=false), leaving one behavioral gap.

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?

Single dense sentence enumerating actions followed by permission rules and one routing sentence; every clause earns its place and the primary capability is front-loaded.

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?

With an output schema present, return values need not be explained, and the description covers the operation set, permissions, and the removal alternative. The only omission is edge-case behavior for duplicate or no-op operations, which is minor given the annotation and schema richness.

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 all four parameters are already documented. The description restates the action values and member identifier formats (phone/JID) but adds little syntax or constraint detail beyond the schema, 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?

Names the specific resource (WhatsApp group members) and enumerates the three concrete operations (add, promote, demote) keyed to the action parameter. It explicitly distinguishes itself from wa_remove_participants, so an agent can select it without inspecting either 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?

States when each action applies and names the sibling to use for member removal, with no ambiguity. It also gives the precondition context (account must be a member, admin for private groups; promote/demote require admin), which tells the agent when the call will succeed versus fail.

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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