AI agents call mean 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.
The mean function performs a read-only aggregation query on numeric field data. It retrieves data and returns a computed statistic with no side effects, modifications to the dataset, or external execution. This is a classic Read operation similar to other sibling tools like 'count_values' and 'dataset_summary'.
From the tool's definition Tool is named 'mean' and described as 'Compute the mean (average) of a numeric field' — this is a statistical aggregation operation that retrieves and computes a value from existing data without modifying, deleting, or executing external operations.
Documented attack patterns abuse exactly the kind of access mean 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 mean:
{
"version": "1",
"default": "deny",
"tools": {
"mean": {}
}
}mean is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Compute the mean (average) of a numeric 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 mean: 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.
mean 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 mean 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 mean. 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.
mean 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.