AI agents call list_icon_sets to retrieve information from Nucleo without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries and returns metadata about icon sets without creating, modifying, deleting, executing code, or moving money. It is a pure data retrieval operation with no capability to alter system state. The low severity reflects that misuse would only expose informational data about available icons.
From the tool's definition Tool name 'list_icon_sets' and description 'List all available Nucleo icon sets with their metadata' indicate a retrieval operation with no side effects. The verb 'list' is explicitly identified in the Read category definition.
Attacks that exploit this kind of access
List all available Nucleo icon sets with their metadata. It is categorised as a Read tool in the Nucleo MCP Server, which means it retrieves data without modifying state.
Register the Nucleo MCP server in PolicyLayer and add a rule for list_icon_sets: 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 Nucleo. Nothing to install.
list_icon_sets 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_icon_sets 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_icon_sets. 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_icon_sets is provided by the Nucleo MCP server (julianallchin/nucleo-mcp). 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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