AI agents call list_servers to retrieve information from MCP-Guide without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The tool retrieves and displays information about available MCP servers organized by category. This is a read-only operation that queries a list without creating, modifying, deleting, or executing any code. It carries minimal risk as it only returns informational data.
From the tool's definition Tool name is 'list_servers' and description states 'List available MCP servers by category' — this is a retrieval/query operation with no data modification or side effects.
Documented attack patterns abuse exactly the kind of access list_servers gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and MCP-Guide, and nothing reaches the server without passing your rules. This is the rule we recommend for list_servers:
{
"version": "1",
"default": "deny",
"tools": {
"list_servers": {}
}
}list_servers 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 MCP servers by category. It is categorised as a Read tool in the MCP-Guide MCP Server, which means it retrieves data without modifying state.
Register the MCP-Guide MCP server in PolicyLayer and add a rule for list_servers: 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 MCP-Guide. Nothing to install.
list_servers 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_servers 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_servers. 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_servers is provided by the MCP-Guide MCP server (qpd-v/mcp-guide). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 5 MCP-Guide tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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5 MCP-Guide tools catalogued and risk-classified — across an index of 42,500+ MCP servers.