AI agents call list_marts to retrieve information from Biomart MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves or queries available marts (biological databases) without modifying data or triggering external operations. It is a discovery/enumeration operation with no side effects, fitting the Read category. Low severity because listing available resources poses minimal risk even if misused by an AI agent.
From the tool's definition Tool name 'list_marts' combined with sibling tools ('list_datasets', 'list_all_attributes', 'list_filters') that are clearly read operations.
Documented attack patterns abuse exactly the kind of access list_marts gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Biomart MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for list_marts:
{
"version": "1",
"default": "deny",
"tools": {
"list_marts": {}
}
}list_marts is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
Free to start. No card required.
list_marts. It is categorised as a Read tool in the Biomart MCP MCP Server, which means it retrieves data without modifying state.
Register the Biomart MCP server in PolicyLayer and add a rule for list_marts: 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 Biomart MCP. Nothing to install.
list_marts 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_marts 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_marts. 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_marts is provided by the Biomart MCP server (jzinno/biomart-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Biomart MCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
8 Biomart MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.