aggregate · MongoDB MCP Server MCP: Risk & Policy

WHAT IT DOES

What aggregate does on MongoDB MCP Server

AI agents invoke aggregate to trigger actions in MongoDB MCP Server. 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

Aggregation pipelines enable execution of complex, multi-stage database operations whose effects depend on the pipeline stages provided as arguments. While typically read-focused, aggregation can trigger side effects through certain stages and represents executable logic rather than simple data retrieval.

From the tool's definition Tool runs MongoDB aggregation pipeline which can execute complex operations including data transformation, filtering, grouping, and computing aggregated values.

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 MongoDB MCP Server, so you can run agents against it safely.

FAQ

Questions about aggregate

What does the aggregate tool do? +

Run a MongoDB aggregation pipeline. It is categorised as a Execute tool in the MongoDB MCP Server 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 MongoDB MCP Server 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 MongoDB MCP Server. 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 MongoDB MCP Server MCP server (ryaker/mongodb-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.