AI agents call slack_channel_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 is a data retrieval tool with no side effects—it queries and returns historical message data from Slack. However, severity is medium rather than low because Slack channel history may contain sensitive information (passwords, API keys, personal data, business secrets), and an AI agent with unconstrained access could exfiltrate substantial amounts of confidential communication.
From the tool's definition Tool description explicitly states 'Read recent messages from a Slack channel' and 'Returns message text, author, timestamp, and thread metadata.' The verb 'read' and absence of any modification or deletion language confirms retrieval-only semantics.
Attacks that exploit this kind of access
Read recent messages from a Slack channel in reverse chronological order. Returns message text, author, timestamp, and thread metadata. Use slack_thread to read replies. 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_channel_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_channel_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_channel_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_channel_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_channel_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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