Slack Note Capture MCP Server

slack_list_channels

Retrieve available Slack channel information to identify channel IDs for posting messages, managing threads, and handling files within asynchronous workflows.

Instructions

List available Slack channels. Use this to find channel IDs.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "slack_list_channels"
  }
}

Input Schema

Name	Required	Description	Default
`types`	No	Channel types to include: public_channel, private_channel. Default: public_channel,private_channel

Implementation Reference

src/index.js:710-730 (handler)

The handler implementation for slack_list_channels in the main switch statement.

case "slack_list_channels": {
  const types = args.types || "public_channel,private_channel";

  const result = await slack.conversations.list({
    types: types,
    exclude_archived: true,
  });

  const channels = (result.channels || []).map((ch) => ({
    id: ch.id,
    name: ch.name,
    is_private: ch.is_private,
    num_members: ch.num_members,
  }));

  return {
    content: [
      {
        type: "text",
        text: JSON.stringify(
          {

src/index.js:227-242 (registration)

The registration of slack_list_channels in the tools list.

{
  name: "slack_list_channels",
  description:
    "List available Slack channels. Use this to find channel IDs.",
  inputSchema: {
    type: "object",
    properties: {
      types: {
        type: "string",
        description:
          "Channel types to include: public_channel, private_channel. Default: public_channel,private_channel",
      },
    },
    required: [],
  },
},

Schema Changelog

Changes observed during successful MCP inspections.

First observedv2.0.0Apr 1, 2026

TDQS

A3.5/5.0

Behavior2/5

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

No annotations provided, so full burden falls on description. Fails to disclose behavioral traits: does not clarify what 'available' means (joined vs all public), omits pagination behavior (critical for Slack APIs), rate limits, or response structure. Only states action without side-effect or resource boundary details.

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, zero waste. First sentence establishes purpose, second provides usage context. Every word earns its place; appropriately front-loaded with no boilerplate.

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

Completeness3/5

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

Matches the tool's low complexity (1 optional parameter, simple action) but leaves gaps given no output schema and no annotations. The ID-finding hint partially compensates for missing return value documentation, but lacks pagination or scope boundaries typical for Slack APIs.

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 baseline 3 applies. The description does not mention the 'types' parameter or add syntax guidance beyond the schema, but the schema adequately documents this single optional parameter.

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?

States clear verb ('List') and resource ('Slack channels'). The second sentence ('Use this to find channel IDs') effectively distinguishes this from sibling message-oriented tools (slack_read_messages, slack_post_message) by clarifying its role in the workflow. Slightly vague on 'available' scope.

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?

Provides explicit usage context in the second sentence ('Use this to find channel IDs'), clearly indicating when to invoke the tool (as a prerequisite for ID-dependent operations). Lacks explicit 'when not to use' exclusions or named alternatives, but the context is sufficiently clear.

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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