Slack MCP Server

list_channels

Retrieve available Slack channels in your workspace, with options to include private or archived channels and set result limits.

Instructions

List available Slack channels in the workspace

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": "list_channels"
  }
}

Input Schema

Name	Required	Description
`includePrivate`	No	Include private channels (requires appropriate scopes)
`includeArchived`	No	Include archived channels
`limit`	No	Maximum number of channels to return

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Feb 21, 2026

TDQS

B3.1/5.0

Behavior2/5

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. While 'List' implies a read operation, the description doesn't address authentication requirements, rate limits, pagination behavior, or what 'available' means in practice. It lacks details about the return format or potential errors.

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 a single, efficient sentence that directly states the tool's purpose without unnecessary words. It's appropriately sized and front-loaded, making it easy to understand at a glance.

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?

For a read-only list tool with no annotations and no output schema, the description is minimally adequate. It covers the basic purpose but lacks details about behavioral traits, usage context, and output format. The high schema coverage helps, but the description doesn't fully compensate for missing annotation and output information.

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%, with all three parameters well-documented in the schema. The description doesn't add any parameter-specific information beyond what the schema provides, so it meets the baseline for high schema coverage without compensating with extra context.

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 description clearly states the verb ('List') and resource ('available Slack channels in the workspace'), providing specific functionality. However, it doesn't explicitly distinguish this tool from its siblings (get_channel_history, search_messages), which focus on message history and search rather than channel listing.

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?

The description provides no guidance on when to use this tool versus alternatives. It doesn't mention scenarios where list_channels is appropriate compared to get_channel_history or search_messages, nor does it discuss prerequisites or constraints beyond what's implied by the parameters.

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

Deploy Server