AI agents call mcp_list to retrieve information from 1MCP Server 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 information about configured MCP servers. It has no side effects—it does not create, modify, delete, or execute anything. It is purely informational, similar to 'list' or 'get' operations. The blast radius of misuse is minimal; an AI agent could at most enumerate available servers to gather information about system configuration.
From the tool's definition Tool name 'mcp_list' and description 'List MCP servers' indicate a query/retrieval operation with no modification or execution of external systems.
Documented attack patterns abuse exactly the kind of access mcp_list gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and 1MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for mcp_list:
{
"version": "1",
"default": "deny",
"tools": {
"mcp_list": {}
}
}mcp_list is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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List MCP servers. It is categorised as a Read tool in the 1MCP Server MCP Server, which means it retrieves data without modifying state.
Register the 1MCP Server MCP server in PolicyLayer and add a rule for mcp_list: 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 1MCP Server. Nothing to install.
mcp_list 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 mcp_list 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 mcp_list. 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.
mcp_list is provided by the 1MCP Server MCP server (1mcp-app/agent). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 17 1MCP Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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17 1MCP Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.