set · Momento MCP Server MCP: Risk & Policy

WHAT IT DOES

What set does on Momento MCP Server

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

WHY IT NEEDS A POLICY

Why set needs a policy

The 'set' operation modifies cache state by writing or overwriting key-value pairs. While this is a write operation (not destructive, as it can be undone), it has medium severity because misuse could corrupt cached data that applications depend on, potentially causing application failures or data inconsistency. Confidence is high because the description clearly indicates a write/modify operation.

From the tool's definition Tool performs 'set a key-value pair in the cache', which creates or modifies data in Momento Cache. This is reversible via subsequent set operations or delete operations.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set Rate-limited

set 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": {
    "set": {
      "limits": [
        {
          "counter": "set_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 Momento MCP Server, so you can run agents against it safely.

FAQ

Questions about set

What does the set tool do? +

set a key-value pair in the cache. It is categorised as a Write tool in the Momento MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on set? +

Register the Momento MCP Server MCP server in PolicyLayer and add a rule for set: 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 Momento MCP Server. Nothing to install.

What risk level is set? +

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

Can I rate-limit set? +

Yes. Add a rate_limit block to the set 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 set completely? +

Set action: deny in the PolicyLayer policy for set. 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 set? +

set is provided by the Momento MCP Server MCP server (momentohq/mcp-momento). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.