Search for messages across Slack channels using query syntax
AI agents call search_messages 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 and queries message data from Slack with no side effects. It does not create, modify, delete, or execute any operations—it only reads and returns existing messages matching search criteria. This is a classic Read category tool with low severity since accidental misuse would only expose information already accessible to workspace members.
From the tool's definition Tool description states 'Search for messages across Slack channels' and server description emphasizes 'searching for messages' and 'retrieve channel history'. The verb 'search' and 'retrieve' indicate data querying with no modification capabilities.
Attacks that exploit this kind of access
Search for messages across Slack channels using query syntax. 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 search_messages: 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.
search_messages 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 search_messages 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 search_messages. 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.
search_messages is provided by the Slack MCP Server MCP server (nikhilchintawar/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.
Teams ship this data inside their own products. See what a licence covers →