aggregate · Legacy Mongodb MCP: Risk & Policy

WHAT IT DOES

What aggregate does on Legacy Mongodb

AI agents invoke aggregate to trigger actions in Legacy Mongodb. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why aggregate needs a policy

MongoDB's 'aggregate' runs a pipeline of operations that can include $out or $merge stages, which write results to collections — making it potentially more than a read. Even without those stages, arbitrary aggregation pipelines execute server-side computation.

From the tool's definition Tool name 'aggregate' on a MongoDB MCP server; description is empty and uninformative.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

aggregate Rate-limited

aggregate stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "aggregate": {
      "limits": [
        {
          "counter": "aggregate_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Legacy Mongodb, so you can run agents against it safely.

FAQ

Questions about aggregate

What does the aggregate tool do? +

aggregate. It is categorised as a Execute tool in the Legacy Mongodb MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on aggregate? +

Register the Legacy Mongodb MCP server in PolicyLayer and add a rule for aggregate: 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 Legacy Mongodb. Nothing to install.

What risk level is aggregate? +

aggregate is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit aggregate? +

Yes. Add a rate_limit block to the aggregate 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.

How do I block aggregate completely? +

Set action: deny in the PolicyLayer policy for aggregate. 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.

What MCP server provides aggregate? +

aggregate is provided by the Legacy Mongodb MCP server (webxspark/legacy-mongodb-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.