AI agents call get_metadata to retrieve information from gnomAD MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves metadata from gnomAD API without modifying, executing operations, deleting data, or moving financial resources. It is a straightforward data retrieval operation. Severity is low because metadata queries cannot cause damage—the worst outcome is retrieving information or overwhelming the gnomAD service with requests, both low-impact scenarios for an AI agent.
From the tool's definition Tool name is 'get_metadata' with description 'Retrieve metadata (v2/v3/v4)'. The verb 'Retrieve' and the read-only nature of metadata access indicate a query operation with no side effects.
Documented attack patterns abuse exactly the kind of access get_metadata gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and gnomAD MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for get_metadata:
{
"version": "1",
"default": "deny",
"tools": {
"get_metadata": {}
}
}get_metadata is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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[gnomAD API] Retrieve metadata (v2/v3/v4). It is categorised as a Read tool in the gnomAD MCP Server MCP Server, which means it retrieves data without modifying state.
Register the gnomAD MCP Server MCP server in PolicyLayer and add a rule for get_metadata: 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 gnomAD MCP Server. Nothing to install.
get_metadata 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 get_metadata 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 get_metadata. 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.
get_metadata is provided by the gnomAD MCP Server MCP server (koido/gnomad-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from gnomAD MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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12 gnomAD MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.