AI agents call filter_list_items to retrieve information from Slack Lists MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Filtering list items is a read-only operation that retrieves or narrows a dataset without creating, modifying, or deleting data. The tool has no side effects and poses minimal risk; misuse would only expose or organize existing data visibility. Low blast radius even if an agent over-filters or accesses unintended items.
From the tool's definition Tool name 'filter_list_items' indicates retrieval/filtering of existing data. Server description emphasizes 'retrieving, filtering, and managing list items' with 'create', 'get', and 'export' as the action verbs for other tools, positioning filter as a read…
Documented attack patterns abuse exactly the kind of access filter_list_items gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Slack Lists MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for filter_list_items:
{
"version": "1",
"default": "deny",
"tools": {
"filter_list_items": {}
}
}filter_list_items is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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filter_list_items. It is categorised as a Read tool in the Slack Lists MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Slack Lists MCP Server MCP server in PolicyLayer and add a rule for filter_list_items: 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 Lists MCP Server. Nothing to install.
filter_list_items 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 filter_list_items 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 filter_list_items. 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.
filter_list_items is provided by the Slack Lists MCP Server MCP server (maplehilllabs/mcp-slack-lists). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Slack Lists MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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5 Slack Lists MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.