AI agents call slack_dm_history 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 historical Slack messages without side effects, placing it in the Read category. However, severity is elevated to 'high' because Slack DM history often contains sensitive information including credentials, personal conversations, business secrets, and confidential discussions.
From the tool's definition Tool name and description both indicate data retrieval: 'Read recent messages' and 'Returns message text, author, and timestamps'. No modification, deletion, or execution described.
Attacks that exploit this kind of access
Read recent messages from a Slack direct message or group DM conversation. Returns message text, author, and timestamps in reverse chronological order. 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_dm_history: 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_dm_history 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_dm_history 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_dm_history. 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_dm_history 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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