Get recent messages from a channel
AI agents call slack_get_channel_history to retrieve information from MCP Server for Slack without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries and retrieves historical message data from a Slack channel. It is a read-only operation that does not create, modify, delete, or execute any actions. The blast radius of misuse is minimal — an AI agent could read sensitive messages but cannot alter Slack state, make financial transactions, or trigger external operations. It falls squarely into the Read category.
From the tool's definition Tool name is 'slack_get_channel_history' and description states it 'Get recent messages from a channel' — purely retrieves data with no modification, deletion, or side effects.
Attacks that exploit this kind of access
Get recent messages from a channel. It is categorised as a Read tool in the MCP Server for Slack MCP Server, which means it retrieves data without modifying state.
Register the MCP Server for Slack 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 MCP Server for Slack. 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 MCP Server for Slack MCP server (z9905080/mcp-slack). 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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