AI agents call sum 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 performs a statistical aggregation (sum) on a numeric field in a dataset. It retrieves and calculates a value from existing data but does not create, modify, delete, or execute arbitrary code. It has no side effects and does not change the dataset state. This is a classic Read operation analogous to a database SELECT with aggregation.
From the tool's definition Tool name 'sum' with description 'Compute the sum of a numeric field across all' indicates aggregation/computation over existing data without modification.
Documented attack patterns abuse exactly the kind of access sum 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 sum:
{
"version": "1",
"default": "deny",
"tools": {
"sum": {}
}
}sum 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 sum of a numeric field across all. 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 sum: 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.
sum 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 sum 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 sum. 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.
sum 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.