AI agents call distinct to retrieve information from FiftyOne MCP Server 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 aggregate information about a dataset field without creating, modifying, deleting, or executing any operations. It is a straightforward read operation that only retrieves unique values from existing data.
From the tool's definition Tool name 'distinct' and description 'Get the list of unique values for a field' indicate a data retrieval operation with no modification or side effects.
Documented attack patterns abuse exactly the kind of access distinct gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and FiftyOne MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for distinct:
{
"version": "1",
"default": "deny",
"tools": {
"distinct": {}
}
}distinct is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Get the list of unique values for a field. It is categorised as a Read tool in the FiftyOne MCP Server MCP Server, which means it retrieves data without modifying state.
Register the FiftyOne MCP Server MCP server in PolicyLayer and add a rule for distinct: 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 FiftyOne MCP Server. Nothing to install.
distinct 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 distinct 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 distinct. 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.
distinct is provided by the FiftyOne MCP Server MCP server (voxel51/fiftyone-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from FiftyOne 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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47 FiftyOne MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.