AI agents call delete_function to permanently remove resources in Open WebUI MCP Server — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.
This tool permanently removes a function from the Open WebUI system. Deletion operations are irreversible and cannot be undone, making this a Destructive action. The severity is high because deleting functions could disrupt workflows, break dependencies, and affect multiple users if those functions are in use.
From the tool's definition Tool name 'delete_function' and description 'Delete a function' indicate irreversible deletion of data/resources. The verb 'delete' is explicitly destructive.
Documented attack patterns abuse exactly the kind of access delete_function gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Open WebUI MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for delete_function:
{
"version": "1",
"default": "deny",
"hide": [
"delete_function"
]
}delete_function disappears from the agent's tool list entirely, and any attempt to call it is denied. The rest of the server keeps working.
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Delete a function. It is categorised as a Destructive tool in the Open WebUI MCP Server MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.
Register the Open WebUI MCP Server MCP server in PolicyLayer and add a rule for delete_function: 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 Open WebUI MCP Server. Nothing to install.
delete_function is a Destructive tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.
Yes. Add a rate_limit block to the delete_function 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 delete_function. 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.
delete_function is provided by the Open WebUI MCP Server MCP server (troylar/open-webui-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Open WebUI MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
82 Open WebUI MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.