Search for users by partial name match across username, display name, and real name. Use this when you need to find users containing specific keywords in their names. Returns up to the specified limit of matching users.
AI agents call slack_search_users 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 queries user information by name/keyword matching and returns results. It is a read-only operation that retrieves data without creating, modifying, deleting, or executing anything. The blast radius is minimal—an AI agent misusing this could only retrieve user profile information already accessible within the workspace, posing no destructive or operational risk.
From the tool's definition Tool description states it 'Search[es] for users' and 'Returns...matching users' — purely a retrieval operation with no modification or side effects. No execution, deletion, or financial action occurs.
Documented attack patterns abuse exactly the kind of access slack_search_users gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Slack MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for slack_search_users:
{
"version": "1",
"default": "deny",
"tools": {
"slack_search_users": {}
}
}slack_search_users is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Search for users by partial name match across username, display name, and real name. Use this when you need to find users containing specific keywords in their names. Returns up to the specified limit of matching users. 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_search_users: 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_search_users 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_search_users 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_search_users. 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_search_users is provided by the Slack MCP Server MCP server (ubie-oss/slack-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 11 Slack MCP Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
11 Slack MCP Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.