whatsmcp

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

TableJSON 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

TableJSON 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.

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

A4.5/5.0

Behavior4/5

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

Annotations already declare readOnlyHint=false, idempotentHint=false and destructiveHint=false, so the safety profile is covered. The description adds meaningful behavioral context the annotations do not: the account must be a member (and admin for private groups) for add, and an admin for promote/demote, which is real authorization guidance for a mutation tool.

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?

Two sentences, front-loaded with the three actions and their effect, followed by prerequisites and the explicit alternative. Every clause earns its place with zero redundancy.

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?

With an output schema present there is no need to describe return values, and annotations cover the safety profile. Between the description's permission requirements and the fully documented schema, an agent has everything needed to invoke this mutation 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 coverage is 100%, so all four parameters (including the action enum-like values and members format) are already documented in the schema. The description restates the action values and member addressing (phone/JID) but adds no syntax or format detail beyond what the schema provides, 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?

States a specific verb+resource ('Add members to a WhatsApp group') and enumerates the three supported actions (add/promote/demote) with their distinct meanings, so the agent can tell exactly what the tool does. It explicitly names the sibling wa_remove_participants as the tool for the opposite operation, cleanly differentiating it from other group tools.

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 explicit prerequisites per action: adding requires the account to be a member (and admin for private groups), while promote/demote require admin. It also states when NOT to use the tool ('To remove members, use wa_remove_participants'), routing the agent to the correct alternative.

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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