AI agents call list_themes to retrieve information from Shadcn Ui without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and returns a list of available themes. It performs a query operation with no capability to modify, delete, execute code, or cause financial impact. The verb 'list' and the passive context ('available themes') confirm read-only behavior. The blast radius if misused is minimal—an LLM cannot cause harm by listing themes.
From the tool's definition Tool is named 'list_themes' with description 'List available tweakcn themes' — a straightforward enumeration operation with no side effects.
Documented attack patterns abuse exactly the kind of access list_themes gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Shadcn Ui, and nothing reaches the server without passing your rules. This is the rule we recommend for list_themes:
{
"version": "1",
"default": "deny",
"tools": {
"list_themes": {}
}
}list_themes is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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List available tweakcn themes. It is categorised as a Read tool in the Shadcn Ui MCP Server, which means it retrieves data without modifying state.
Register the Shadcn Ui MCP server in PolicyLayer and add a rule for list_themes: 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 Shadcn Ui. Nothing to install.
list_themes 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 list_themes 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 list_themes. 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.
list_themes is provided by the Shadcn Ui MCP server (jpisnice/shadcn-ui-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Shadcn Ui, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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10 Shadcn Ui tools catalogued and risk-classified — across an index of 43,000+ MCP servers.