slack_list_channels
Lists channels in a Slack workspace, including public channels, private channels, and direct messages (DMs). Reads from the local IndexedDB cache — only channels that Slack Desktop has synced to disk are returned. Pass workspace_id from slack_list_workspaces to filter to a specific workspace.
This record as markdown: /tools/com-local-mcp-local-mcp/slack-list-channels.md
What slack_list_channels does on Local
AI agents call slack_list_channels to retrieve information from Local without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
| Parameter | Type | Required | Description |
|---|---|---|---|
limit | integer | — | Max channels to return (default 200) |
workspace_id | string | — | Workspace ID from slack_list_workspaces (optional — omit to list channels across all workspaces) |
Parameters from the server's own tool schema.
Why slack_list_channels is rated Low
This tool retrieves and lists existing Slack channels and DMs with no side effects. It is a read-only operation that queries cached data already synchronized by Slack Desktop locally. While it provides access to channel information (potentially including private channels), the capability to list these is a standard read operation with no destructive, write, or execution capabilities.
From the tool's definition The tool 'Lists channels in a Slack workspace' and 'Reads from the local IndexedDB cache'. It performs a query/retrieval operation without modifying or deleting data.
Attacks that exploit this kind of access
The rule that runs slack_list_channels safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Local, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For slack_list_channels, this is the rule to start with:
slack_list_channels is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Local, apply this rule, and every slack_list_channels call is checked against it from then on.
Questions about slack_list_channels
Lists channels in a Slack workspace, including public channels, private channels, and direct messages (DMs). Reads from the local IndexedDB cache — only channels that Slack Desktop has synced to disk are returned. Pass workspace_id from slack_list_workspaces to filter to a specific workspace. It is categorised as a Read tool in the Local MCP Server, which means it retrieves data without modifying state.
slack_list_channels accepts 2 parameters: limit, workspace_id. The full parameter table on this page comes from the server's own tool schema.
Register the Local MCP server in PolicyLayer and add a rule for slack_list_channels: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Local. Nothing to install.
slack_list_channels is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the slack_list_channels rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for slack_list_channels. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
slack_list_channels is provided by the Local MCP server (local-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
More on Local, and thousands of servers like it.
This server
Across the catalogue