AI agents call list_blocks to retrieve information from Shadcn without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and displays available UI blocks from the shadcn/ui library. It performs a read-only operation that queries data without modifying, deleting, executing code, or creating financial obligations. The blast radius of misuse is minimal—an AI agent cannot cause harm by listing available blocks.
From the tool's definition Tool name 'list_blocks' and description 'List all available shadcn/ui blocks' indicate a query/retrieval operation with no side effects.
Attacks that exploit this kind of access
List all available shadcn/ui blocks. It is categorised as a Read tool in the Shadcn MCP Server, which means it retrieves data without modifying state.
Register the Shadcn MCP server in PolicyLayer and add a rule for list_blocks: 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. Nothing to install.
list_blocks 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_blocks 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_blocks. 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_blocks is provided by the Shadcn MCP server (@magnusrodseth/shadcn-mcp-server). 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.
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