slack-mcp

send_group_dm

Destructive

Send a message to a group DM with multiple Slack users. Provide user IDs and the message text to deliver it directly to the group conversation.

Instructions

Send a message to a group DM (multi-party direct message).

Args: user_ids: List of 2+ user IDs to include in group DM message: Message text to send

Returns: True if message sent successfully, False otherwise

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": {
      "user_ids": "<user_ids>",
      "message": "<message>"
    },
    "name": "send_group_dm"
  }
}

Input Schema

Name	Required	Description	Default
`blocks`	No
`message`	Yes
`user_ids`	Yes
`unfurl_links`	No
`unfurl_media`	No

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Aug 30, 2026

TDQS

B3.2/5.0

Behavior3/5

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

Annotations already indicate a mutating, non-read-only action (destructiveHint=true, readOnlyHint=false), and the description adds a useful True/False return contract. It does not discuss side effects, unfurling behavior, or optional fields, so the transparency is adequate but not rich.

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?

The description is compact and well organized: a one-sentence purpose, a short Args list, and a Returns line. Every sentence contributes, with no filler or redundancy.

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?

Even with an output schema present, a 5-parameter tool needs more context than this. Three optional parameters are unexplained, no guidance is given for selecting this tool over send_dm, and the failure behavior beyond 'returns False' is not described.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters2/5

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

The description adds meaning for user_ids ('2+ user IDs') and message ('message text'), but schema description coverage is 0% and the optional parameters blocks, unfurl_links, and unfurl_media are completely undocumented. With low coverage, the description needed to compensate for these gaps and did not.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The opening phrase 'Send a message to a group DM' gives a specific verb, resource, and scope, and 'multi-party direct message' distinguishes this from ordinary DMs. It does not explicitly contrast with siblings like send_dm or post_message, so it falls just short of a perfect score.

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

Usage Guidelines3/5

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

The requirement that user_ids must contain '2+' users implies this tool is meant for group conversations, giving some usage context. However, the description never states when to use this instead of send_dm for one-to-one DMs or post_message for channels, and it names no alternatives or exclusions.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.