Get recent messages from a Slack channel
AI agents call slack_get_channel_history to retrieve information from Slack MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves historical messages from a Slack channel without modifying, deleting, or executing any operations. It is a query operation that reads data. The severity is low because message history retrieval has minimal blast radius—the worst outcome is unauthorized information disclosure, but it does not modify state, execute commands, or cause financial impact.
From the tool's definition Tool name 'slack_get_channel_history' and description 'Get recent messages from a Slack channel' indicate a retrieval operation with no side effects. The verb 'Get' and the read-only nature of querying message history align with the Read category.
Attacks that exploit this kind of access
Get recent messages from a Slack channel. It is categorised as a Read tool in the Slack MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Slack MCP Server MCP server in PolicyLayer and add a rule for slack_get_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 Slack MCP Server. Nothing to install.
slack_get_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_get_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_get_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_get_channel_history is provided by the Slack MCP Server MCP server (sdancy10/slack-mcp). 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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