AI agents call slack_list_channels to retrieve information from Access without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves channel metadata without modifying, deleting, or executing any actions. However, severity is elevated to 'high' because: (1) it enumerates all channels including private ones, exposing workspace structure and membership information; (2) this is a credential-store server proxying authenticated API calls on behalf of the agent; (3) listing all private channels without per-channel permissioning is a…
From the tool's definition Tool name is 'slack_list_channels' and description states it 'List[s] all Slack channels' with 'IDs, names, topics, and member counts.' The verb is 'List' which is a read-only retrieval operation.
Attacks that exploit this kind of access
List all Slack channels (public and private) in the workspace with their IDs, names, topics, and member counts. Use this to find channel IDs needed by slack_channel_history and slack_send. It is categorised as a Read tool in the Access MCP Server, which means it retrieves data without modifying state.
Register the Access 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 Access. 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 Access MCP server (scottpedia0/access). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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