wwebjs-mcp

groupChat_addParticipants

Add participants to a WhatsApp group chat by specifying the chat ID and participant IDs. This tool directly expands group membership.

Instructions

[Group Chat] Add the participants. Add a list of participants by ID to the group

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "sessionId": "<sessionId>"
    },
    "name": "groupChat_addParticipants"
  }
}

Input Schema

Name	Required	Description
`chatId`	No	Unique WhatsApp id for the given chat group
`options`	No	Options for adding participants
`sessionId`	Yes	Unique identifier for the session (alphanumeric and - allowed)
`participantIds`	No	Unique WhatsApp identifiers for the participants

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Aug 2, 2026

TDQS

B3.1/5.0

Behavior2/5

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

With no annotations, the description carries the full burden of behavioral disclosure, but it merely restates the schema. It does not mention side effects, permission requirements, whether participants are added silently or trigger invites, rate limits, or error conditions.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is very brief and front-loaded, but the two sentences are slightly redundant ('Add the participants' and 'Add a list of participants...'). Still, it is concise and wastes no words, though it could consolidate the message.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a tool with a nested options object and four parameters, the description is under-specified. It omits return values (no output schema), prerequisite conditions, and the specific behavior when adding participants. The schema covers parameter names but not the tool's overall context, making this insufficient for complex usage.

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 the baseline is 3. The description's phrase 'by ID' adds no information beyond the schema's 'participantIds' description. It does not explain the 'options' object structure or that 'chatId' is required conceptually despite not being marked required.

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 clearly states the action ('Add') and the resource ('participants' to 'the group'), making it unambiguous. It distinguishes itself from sibling tools like groupChat_removeParticipants and groupChat_promoteParticipants by specifying the add operation.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

No guidance is provided on when to use this tool versus alternatives, nor any mention of prerequisites (e.g., admin rights, group membership). The description only states the action without contextualizing it among the sibling group management tools.

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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