Claude Code Slack Channel

send_slack_message

Send a Slack message to a channel using its ID and markdown text, enabling replies to incoming webhook messages.

Instructions

Send a message to a Slack channel. Use this to reply to webhook channel incoming messages from Slack.

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": {
      "channel": "<channel>",
      "text": "<text>"
    },
    "name": "send_slack_message"
  }
}

Input Schema

Name	Required	Description	Default
`text`	Yes	The markdown text reply to send to Slack
`channel`	Yes	The Slack channel ID to send the message to (e.g. C0AMZUV0JTZ)

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Sep 6, 2026

TDQS

A3.8/5.0

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. It indicates the message-sending action, but does not mention authentication requirements, permission prerequisites, rate limits, failure behavior, or whether the message is immediately visible to others. This is minimal behavioral context.

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 two sentences with no filler. The core purpose is front-loaded, and the additional usage guidance is concise and directly useful.

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?

For a simple, two-parameter send action with fully documented parameters, the description provides sufficient context: what the tool does and when to use it. Missing authentication and response details are notable but not critical for this simple operation.

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?

The schema already describes both parameters with 100% coverage, including that text is markdown and channel is a Slack channel ID. The description adds little beyond the schema, so the baseline score of 3 is appropriate.

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 a specific action ('Send a message to a Slack channel') with a concrete resource and format. It also narrows the intended use case to replying to webhook channel messages, making its purpose unmistakable even without sibling tools.

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

Usage Guidelines4/5

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

The description explicitly tells the agent when to use the tool: to reply to webhook channel incoming messages from Slack. There are no sibling tools or exclusion conditions, so the usage guidance is appropriately clear for the context.

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

Deploy Server

Other Tools

send_slack_messageA