create-index · Mongodb3 MCP: Risk & Policy

WHAT IT DOES

What create-index does on Mongodb3

AI agents use create-index to create or update resources in Mongodb3 — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Mongodb3 environment.

WHY IT NEEDS A POLICY

Why create-index needs a policy

Creating an index modifies the collection's metadata and storage structure, making it a Write operation. While indexes can be dropped (reversible), creating them impacts database performance and structure. Severity is medium because index creation on large collections can be resource-intensive and affect query performance, but it is not destructive and does not cause data loss.

From the tool's definition Tool name 'create-index' and description 'Create an index on a collection' indicate this tool creates/modifies database metadata (indexes) which is a reversible operation.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

create-index Rate-limited

create-index stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "create-index": {
      "limits": [
        {
          "counter": "create-index_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Mongodb3, so you can run agents against it safely.

FAQ

Questions about create-index

What does the create-index tool do? +

Create an index on a collection. It is categorised as a Write tool in the Mongodb3 MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on create-index? +

Register the Mongodb3 MCP server in PolicyLayer and add a rule for create-index: 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 Mongodb3. Nothing to install.

What risk level is create-index? +

create-index is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit create-index? +

Yes. Add a rate_limit block to the create-index 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 create-index completely? +

Set action: deny in the PolicyLayer policy for create-index. 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 create-index? +

create-index is provided by the Mongodb3 MCP server (mongodb3-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.